I am not a big fan of prorietary stuff myself, and to be honest, it's one of the reasons I avoided Nvidia for a long time.
It's the same reason I avoided Sony stuff for a long time.
Particularly, with Nvidia, the likes of Physx and G-sync. Physx could have been fantastic, had they been more open with it.
G-sync? Well, I simply won't buy a monitor that ties me to a particular GPU vendor. Simple as...
Why did I go Nvidia? I simply fancied a change last year after so many years with AMD, and 3D support is a bit less hassle.
Why did I stick with Nvidia this year? I just found the overall experience with Nvidia to be really good. Just less hassle, and no hardware issues at all.
Where GW is concerned though, I honestly am not concerned for AMD users right now. Maybe it will turn out to be this nasty thing you guys are worried about, but if that's the case, then it won't see much adoption... meaning, at best, we get occasional eye candy benefits.
EDIT:
Also, please note that Flex will have a direct compute path, which means it should work just fine on AMD hardware. In theory. And I hope that turns out to be true.
AMD had shocking Drivers back when i had a 6950, no doubt about that.
Having said that AMD got a lot of stick for bad drivers back then, and rightfully so, they have worked very hard to improve things. and improve things they have.
For about a year now AMD's Driver have been just as solid and stable as Nvidia's, infact Nvidia had some problems last year with their drivers where AMD didn't.
As For PhysX, the only game i was impressed with that was Borderlands 2. but thats one game.
The problem with PhysX is that it is prorietary, overall Devs have very little interest in it, it seems to me 99% of them have no inclination to do anything serious with it, if they even bother with it at all.
'Physics' is actually used a lot in games, BF3/4 Crysis 3, even Farcry 3 has a lot of Physics in it, you shoot at wooden crates they break up in to splinters flying about, spark flying about when shooting at metal objects.
You don't need Nvidia PhysX to have those sort of effects in games, it may not look as good. but its improving all the time.
I cannot help but feel that if Nvidia PhysX was an open API very wide uptake will have happened, and Devs will have done far more with it.
As it stands i'm not paying over the odds for a lesser GPU just to have effects in the odd game here or there that you see in every other game, only a little less pretty, though i would argue that what you see in BF4 is more impressive than anything i have ever seen in an Nvidia title.
G-Sync, i think that can be done without the cost implications, and i think AMD will do exactly that.
Oh, PS: TressFX is Physics.
