At the time, the GTX680 and 7970GHz were pretty competitive. I am better off with the 7970 than GTX680 for sure today, but for me that was simply because AMD launched first so I grabbed it, a little luck I guess. But, remember back when the 7970 launched and the GTX580 was it's competition, AND more expensive at the time? Anyone with a GTX580 has probably had to upgrade by now.
The difference today between 580/680/770 2GB can be massive depending on the game. 3GB of VRAM, a lot more memory bandwidth and GCN architecture driver support have delivered, while GTX680/770 are aging very poorly against its former direct competitor.
280X is
21% faster than 770 at 1080P
280X is
29% faster than 770 at 1440P.
And it's only getting worse. While R9 280X can easily play some modern AA games, even at 1440P, 680/770 are getting destroyed.
In Rainbox 6 Siege, 280X is more than
75% faster than 680/770 at 1440P.
In Just Cause 3, 680/770 are barely in the 40 fps range.
In SW:BF, 280X completely dominates 680/770.
In Mortal Kombat X, 280X once again demolishes 680/770.
In Batman AK, you can run the highest textures on R9 280X/7970Ghz, something not possible on 680/770 2GB cards.
Same story with Formula 1 2015 or Titanfall, etc.
Older games? 280X/HD7970Ghz continues to smoke 680/770.
I think that if someone felt the need to upgrade from a 680 it's likely that they would also feel the need with the 7970, both can't handle games with the kind of performance they offered back in 2012 or near what a current $500 card can deliver..
While it's pointless to compare a modern $500-600 card to a 4-year-old 7970, a 7970Ghz / OC user can slice through a decent amount of modern titles with ease in situations where 680/770 2GB are miles behind. With the combination of PS4/XB1 being so underpowered, and most modern PC games being mere console to PC ports with minor upgrades, it's no wonder that an overclocked 7970 can play many modern AAA games at 1080P High/VHQ settings 4 years since launch.
Think about how many PC gamers purchased GTX750/750Ti/950/960/R9 380 this generation and the HD7970 OC / R9 280X beats all of those cards, while matching the 380X. Theoretically that means if a 950/960/R9 380/380X user keeps his GPU for another 2 years, HD7970/R9 280X can still be used at similar or better settings for the same period.
but things can change very quickly during 2016.
I hope so. I sure don't want 2016 to be a console ported year like most of 2015 was. Nothing diminishes the desire to get a new $600+ GPU when the underlying game is outdated on day 1 and looks like a 97% console port with sprinkles of some PC specific tech. PS5/XB2 cannot get here fast enough and it's only been 2 years into this current gen console cycle.
If some future PC games use UE4, then 7970 won't be able to handle those games well but thus far the major studios aren't embracing UE4.
The 7970 has had the same staying power as the 9700Pro its been a great card.
I think 7970 OC has the most relevant staying power compared to even 9700Pro or 8800GTX U. That's also a function of PC gaming not advancing from a technical point of view as fast as the in old days. Looking at SW:BF though and how well 7970 does in it, if a lot more PC games were as well optimized, 7970 could last another 2 years for 1080P.