The last expansion didn’t do much for me either, but that’s because I have an ingrained aversion to espionage systems stemming from… every single strategy game I’ve played with them. :) So I never really touched it.
I wouldn’t expect them to ever extend the timeline or do much with regards to post-WW2, they don’t seem to have any interest in that. I don’t think they can get much mileage out of it since most games are wrapped up by then. Mods are your best bet for that sort of thing, IMO. The Soviet expansion should come with new mechanics and won’t “just” be a focus tree, although it remains to be see how much those mechanics might add to the game. I imagine they’ll start talking details soon.