I would like Hornby to consider having a go at the Isle of Man narrow gauge line. Also London Underground deep tube stock from the 1950's as well as surface stock from the same period. Some RTR London Trams would also be nice. Lastly to do some early era Southern Region EMU's such as Bulleid 4-SUB, 4-LAV, 4-NOL, 4-COR, etc.
There are lots of opportunities to make more coaches. There are lots of new locomotives being introduced that do not have appropriate coaches to haul.
However what I expect is another version of Flying Scotsman and yet another version of the LNER A4 Mallard.
Model railways is all about nostalgia and there are plenty of opportunities still for Hornby to explore and it's not all about locomotives.
Regards Stephen.