Tbh Bachmann is very much backlogged so I would be surprised if we got anything new molds this year.
Maybe 2024 can can just be a big re-release year. Here are some products they can rerelease.
Arry
Bert
M wagon
Tar tanker
Well wagon
Ice cream van
Cream tanker

Arry and Bert prob won't happen yet as Doug said salty in on hold .

•The m wagon could come back maybe with a rock load I doubt this would happen this year
•The tar tanker and cream tanker could come back at the same time .
•The wellwagon could come back with miniature engine load .
The ice cream van could be a LNER 12 ton van .

Now as for new products for HO
works unit coach or slip coaches
Troublesome truck 7
 Maybe the breakdown train 

Narrow gauge I feel we are gonna say goodbye to the L&B wagon which I don't want to happen but it's inevitable Hopefully they reuse the tooling , and make it into a standard gauge version from season 2 for n scale
However for new products  Red and blue open top carriages  are prob what we can expect 

Trevor could also happen this year as they have started doing road vehicles again.

Diesel 10 would be super cool to see I think he would sell very well .
He would be cool to see but pinchy would be hard to do but it could happen.

If Diesel 10 had a removable Pinchy he could happen . Bachmann makes a GG1 with high pantographs which is taller then diesel 10 now if Pinchy was a separately attached piece that is removable it could work well . I really think diesel 10 is a perfect model for Bachmann to make . We need a large diesel in the Thomas range that can haul freight trains and Diesel 10 is the perfect and only option .

I do think whiff is a good idea but the only question is how would they do his glasses

No I think whiff would make a great addition to the range same with Rocky tbh we need some Maintenance stuff for the range .
Rocky is a great ideal start to this . Diesel 10 and Harvey are some other examples they just need to get there attachments done right maybe you can take pinchy on or off .
The works unit coach is another maintence item same with Judy and Jerome .

The only question is how to whiff glasses

After a long time of looking at these vans Bachmann has yet to make a fireworks van - they make the explosives vans but no fireworks van
Ice cream van rerelease - a new n scale release but the HO one is retired for some reason Bachmann please bring this back .
Lei is a Chinese van who could be seen not as troublesome truck 7 but a release sorta like scruffy I guess .

I also think Troublsome truck 7 needs to be a van prob a brown or orange one

Predictions and hopes for 2024 .
Edward
Henry
Cattle wagon
TT#3
TT#4
Tidmoth sheds
Red branchline coaches
Museum coaches 
Gordon express set
Thomas saves Santa

2024 is just down the corner that means the spring announcements are soon so here are my predictions for HO and NG .

•Winston - we already have him in large scale about time we got him in HO .
•Skiff - unpowered we have the Harwick crew but where is he .
•Troublesome truck 7- we have been talking about this forever it should be a van with the face that says oh look Henry's spooked .
•Well wagon black with Mike load 
•Well wagon gray with Bert load
•Well wagon brown  with Rex load
•Slip coach - due to a questionable release that can allow carriages uncouple automatically realistically can happen

• Ice cream van - rerelease
• sound wagon that has sounds from the show chuffing , station sounds , etc

Narrow gauge

•Open red coach
•Open blue coach
•Orange V tipper wagon
•Gray V tipper wagon
•Refreshment coach

Trevor

EZE track level crossing

DCC Thomas and Percy set

American to European coupling adaptor.

Updates to existing models
Thomas - new face and back lining
Henrietta - face

The only new engine if you can count it as one is Winston this is due to a back log of products Bachmann open coaches will come in both colors as Bachmann likes making red and blue versions of NG rolling stock . Not to mention they accidentally made blue open coaches NG in S17.

Arry and Bert as an exclusive is a good idea . Arry and Bert I think if brought back will sell better then then they originally  did . Arry and Bert appear throughout many seasons of the show and I think they would sell well now . Maybe give Arry a different face to tell them apart or maybe Bert . That way you have a reason to buy them again . However due to salty being delayed idk if it can happen anytime soon .

The CGI mandate makes no sense since the show ended 3 years ago and Mattel is marketing something that Bachmann will never touch

12 tons vans are cool I plan on buying a few such as the mr.jolly chocolate vans , or the funfair ones that are announced , maybe one or two blue ones for the flying kipper. These are really cool and underrated .

I hope they make more of these maybe a brown one with the iconic face 26 on the reference sheet it's a funny face and has done so much in the show from bullying  Oliver to yelling Henry's spooked . THIS SHOULD 110% be troublesome truck number 8 . It would also have no vents .


I also want them to  bring back the ice cream vans I would for sure buy them . As G and N has them but no HO why did they retire them I hope they bring back the OG Bachmann 12 ton van .

I had done a rolling stock list here is an engine list .

Diesel 10
Flying Scotsman
Harvey
Nia
Hiro
Glynn
Stephen
Whiff
Scruff
Arry
Bert 
Porter 
Sidney
Ashima
Merlin
Young boa
Philip
Skiff
Winston
Belle
Gina
Mainland shunter
Some characters that can be repaints


Millie
Victor
Luke
Tamikia- ng Australia  characters   
MightyMac - use existing basis model
Duke - your running out of narrow gauge engines to make to rule could be exempt
Mid Sodor repaints
No way there making Freddie not even the fans care for him
 
I hope this opens up a huge discussion here

Bachmann is gonna make a cgi Duncan they use those reference photos if they are gonna redesign salty they won't make a model era style  Duncan .

To be honest there are few Ho scale items that have yet to be released such as Beau who seems to be done for a while I know theses boxes take time but it seems the development of these process is short compared to the time period of a final design to stores .

With a lot of engines narrow and standard now when are they going to make the Aresdale railway . They don't have Z scale track but they could make it here is my idea .
So in the season 24 episode the little railway show duck Oliver and Ryan take Mike Rex and Bert to ulfstead castle in well wagons .
So the well wagon is something I would love to see Bachmann bring back here is how they can do it with the Aresdale  railway .
Have the engine and the tender be detachable from the wagon and have a track of them to sit on . That would also be removal . The track would be z scale and the engine would be able to freewheel


Rex with tender on well wagon
Mike with tender on well wagon
Bert with tender on well wagon
How would you do them be realistic I doubt Bachmann would start making z scale for these three

I think all of these are good ideas . I would also like to see Hernettia gain a face . I think that all the pre 2005 faces are in need of a update Bertie needs a full update for sure cranky is so out of scale I would love to see a $100 new model of him that is way better . Harold also needs an update but is not needed 100% maybe update the colors of S.C. Ruffy to be his rebuilt condition .