If you want to ask anyone specifically about the Shadow, Mim's your man since he's been playing a DPS Shadow through ops and is quite skilled even without using the ONE move you're pinned all of your hopes on.
The DPS players I've played with and the DPS toons I play seem to do just fine without them because the players involved know how to adapt. If you don't know how to adapt or are too rigid to adapt then that's on you.
If you can't find a way to get more DPS out of your toon when you've lost your crutch move, that's your queue to start adapting.
My Vanguard tanking has to adapt too in 2.0 since there are a lot of changes with my class and role too. I'm not going to sit here and bitch and moan about having to relearn all this stuff and spend time and effort having to go over my rotations and priorities. I'm just going to do what I need to do to get efficient at the new system.
Another example, my Marauder who uses the Carnage tree has also had some major changes which a lot of people aren't happy with. We have a harder job of keeping up buffs and rage and it's just gotten even harder. A lot of people are complaining about it but a lot of people are also trying to figure out what BioWare had in mind with these changes since a lot of changes were made... NO ONE is talking about the loss of Pommel Strike and Savage Kick (yes, we get TWO trashkill moves) because there are so many abilities so much more important to be worried about that have wider and more important uses.
Changes have been made, more changes will be made... everyone continues to try to figure out the best way to get the most DPS or threat or healing or whatever out of changes when they're made.