You pretty much go where the money is...
I had & raced Mopars for over 35yrs and if I got a deal with GM or Ford I'd be stupid not to go with it, that doesn't mean I wouldn't still own Mopar's...
It's a tough business to be in and make a living, no money, no racing simple as that....
Pro Stock is pretty much gas power funny cars anyway.
Nothing stock about those cars except for the name & fuel...