You're 8 or 9 years too late. Sunset/3rd Rail did the streamlined P-7d and Cincinnatian cars in 2015. Only 40 3-rail and 10 2-rail locomotives were supposed to be made.
I assisted with this project on behalf of GGD and 3rd Rail in July of 2015, so yes 8 years late. 50 total P7-Ds were indeed made. While finding one on the secondary market is not likely anytime soon, there were more car sets made. The P-7E was made in larger numbers.
As for the future and new items, lots of great ideas here, but the reality of the O scale marketplace is a tough one. Plastic diesels seem to do best only because there are enough road names to meet the MOQ for a sales price that is acceptable to the buyer. Locomotives that only were ordered by a single or a very few roads probably won't get the orders to go forward. Remember the E60? I preordered 3 as did several other people I know, and we couldn't get the units to go forward on it.
Plastic tooled passenger cars render detail the best, but that is a lot of cars that need to be sold to offer them at a cost that the market will bear. Heavyweight cars are most economically done in plastic. Brass is getting to the unobtanium price for cars these days so even a single car let alone a full train is extremely expensive.
We probably won't see new steam locomotives very often. As a transition modeler myself, I would love to see several steam locomotives made, but we suffer as a hobby community on the inability to agree on a steam locomotive that could sell in the kinds of numbers, even in brass, that is required to make the project viable. The NYC H10s may very well be the last steam we will see for the time being.
However, I don't want to be overly negative. There are some great projects in development and some interesting ones coming down the road. I am personally excited that Superliners are moving forward along with Genesis and Charger locomotives. The Eagle is in production as is the SD40-2 which has been a long time coming, but I think it has been worth the wait. FA's while a 2024 project aren't that far off. Reruns are only being done now to fill gaps between the new offerings and not being done as a replacement for newly tooled trains unlike other manufacturers. The future of scale O is exciting and all I can conclude with is keep your ideas coming!