It would appear that the most recent issue of PC Pilot has an interview with Matt Wagner about the status of Modern Air Combat, and clears up some of the information surrounding this new title.
Although I don’t have direct access to the article, it would appear to those who have read it that the new title is going to be completely separate and apart from the main DCS World client, a totally different .exe. However, one thing that is still sort of muddled is the status of those owners of FC3 and how it will integrate into their user interface. The new product will have its own GUI, its own folders, and be pretty much separate and apart from DCS. There is also some indication that the maps within the game will be on the smaller side.
Some questions still seem to be asked about its MP integration with DCS:W, and it there are conflicting reports about whether or not MAC aircraft and DSC:W aircraft will be occupying the same space on servers. I sort of doubt it considering the lengths the developers are going to in order to state categorically that these will be two completely different titles.
Should be interesting if you’re into this sort of thing.