Not the right place to look for information, normally you won't really find anyone know anything about DCS in this dying forum.
And in this forum you hardly find friendly people explain you things clearly, it's just sad
Go to Eagle Dynamics' official forum for DCS, that's the place to go. This forum doesn't allow me to include URL in my reply but you can find it easily by just searching it online.
Now for your question, the situation is that, the new Nevada map is developed using completely new graphic engine EDGE came out with the new DCS 1.5/2.0, yet the old Caucasus map was developed based on the old graphic engine in DCS 1.2.x. So naturally there is huge compatibility issue when they port the old Caucasus map into the new DCS 1.5/2.0 environment. With such a huge map in a complex graphic engine many problems take time to be addressed and fixed, plus the Nevada map is still in Alpha, and is in fact still in active development. In this circumstance ED decided to divide the product line into two separate official version (current DCS 1.5) and the open alpha (the 2.0) to better redirect resources to the most needed place. Personally I think this is a good decision.
So yes, eventually the standard official version will be updated from 1.5 to 2.0 once Nevada is finished and there will be only one version by then, in which you can use both map in the same game platform, switching between two different maps in the mission editor, etc.
Hope that make sense.
And no, I am not an official from ED, I'm just a normal simmer telling you what I read and understood from the official information released in the official forum.