Well, I would buy a 970, then. Consider this: PS4 will soon have a price drop. I mean, this is the first console (with One) receiving deep discount one year after the official release (just look at PS4+GTAV+Last of Us bundle), so for sure they will cut the price soon. You can always buy it later, anyway. The same is for Uncharted 4. Just wait for a Greatest Hits, Platinum, Goty edition or so. Game on console are expansive, too much. Even with deep discount, they are expansive. I had a PS4, I sold it (pretty much the same price I paid for it), then I bought a good PC. And a 970 too. Yeah, it was expansive anyway, but remember: on PC you can grab most all titles very cheap. You can find Witcher 3 around 20$, for example.
So: if you want play Witcher 3 NOW, you would pay around 400€ (a 970, Ground Zeroes and Witcher 3, full price, presuming GZ will be 20€
.
Otherwise, if you want play it on console, the cost is 511€ (again, I considered italian price for boxed, retail games plus the console itself).