Their slow pace and suspected lack of focus have been a discussion before on several occasions.
I believe they just want to do too much at the same time and that might endanger the proper progress of DCS. This is made even worse by the community on the official boards; every time someone tries to post something even remotely critical about the development process of DCS he gets jumped on immediately causing the thread to transform in an immediate flamewar.
I haven't kept up to date on the Mig project as I am not very interested in the aircraft, but if its true that the project is in limbo that would be a rather big blow for DCS. It was the one thing that was on the horizon to be released with a proper 'DCS' realism label and many many people were looking forward to it.
I just wish ED would be more up to date on telling us what is going on, instead of the more generic 'we're still working on it' posts with the odd screenshot thrown in.
I agree that DCS singleplayer is not very strong. I enjoy it as a multiplayer platform on a private server with a great bunch of guys. We have created a nice version of the map with different training areas, AAR options and a live fire enemy danger zone.
But it's all more procedurally oriented (learning how to employ the A-10 successfully) instead of having an action packed narrative. Well, we make that ourselves I guess.

But for a cool SP experience Falcon still reigns supreme IMO. At least for Modern Day ops.