I've been playing this game for quite some time now and have nearly filled up my whole entire Museum with German-Soviet tanks. The only issue I have is that, the space is running out, I was hoping to have enough space for British-American sections. Which is why I'm writing this suggestion;

The Museum should receive an update where there could be pre-made or adjustable sections of it. So, what I'm trying to visualise is one section pre-made or custom made for Soviet tanks and stuff and another one for German! And maybe even add some new props like place-able flags.

And about the Japanese part of the subject, I think it would be very easy to perfect some Japanese tanks for a DLC, an example of a tank thats widely known is; Type 95 Ha-Go, a tank widely used during their regency. There's plenty of documentaries and blueprints to go over to make the perfect mock up of it.

That's my idea, anything I've listed is of course debatable and arguable.