From what I understand, the '70s/'80s setting is just for flavor, but in the future could it be used to affect gameplay? For instance if you have units of mixed Western and Eastern Bloc soldiers, they may not work as well together at first. While modeling loyalty/unit cohesion might be too much, maybe it just decreases some of their stats during a mission? On a strategic level, if you undertake too many missions in one region while ignoring another, you get penalized by the neglected region; this is just like in the original X-COM, except maybe this extends to not just one geographic region (like North America or Western Europe), but all of the regions of a bloc.
And just which are the current funding nations anyway? I assumed that so far it's just NATO and Warsaw Pact countries, but it looks like Australia and New Zealand are out there too. I'm curious if China or the Non-Aligned Movement countries (especially India, Yugoslavia, Egypt, and Indonesia) could send troops as well. Or what if they're kept in the dark entirely? So if you undertake missions in their territory, their local forces might compete with you, or even fire upon you.
I know all of this adds another layer of complexity and so is probably not feasible right now, but it's interesting to think about.