Bill has hit the nail on the head, in my opinion.
I am not a FS developer - just a user. But I have noticed that, even though there has always been a "learning curve" in all things relating to computers, that learning curve never seems to flatten out - the angle of it keeps on rising.
So, it seems to me that there have been MANY FS hobbyist developers who have achieved terrific things in recent years - but who have finally "dropped out" . I won't attempt to name these people - but most of them are not teens, nor 20 somethings - nor are they mere children of 30's or even 40's . I won't go any further - perhaps you can get my drift. But for various reasons, in spite of their enthusiasm, FSx has become just "a Bridge too Far" !
Maybe a younger crowd will indeed pick up what is required to master FSX development - but, who knows, - it is now a defunct programme. Still alive theoretically - but with a very definite future lifespan. Then again - there are many who still maintain enthusiasm for CFS2, and good wishes to them.
Barry