This is what you get for spying on each and everybody and infiltrating everything. So now they distrust everybody and (rightfully) are asking for the source.
The result will be that they then will have the source and will do their own improvement and not coming back for more. This basically means that they can do one more deal by selling the software and then they will start selling the software themselves (including the backdoors)
So the wise thing would be NOT to sell anything. However if just one company will sell, they are all lost.
I am not even worried about the backdoor, because that was in there already.
The next will be that they ask the source code for other software as well (Microsoft anybody?)