By the time you require the performance a 690 offers, there'll be faster cards out at half the price. "Future proofing" is never a good idea to go for when it comes to graphics cards. It makes the most sense to buy for now, you'll get better use out of your money.
yes the 690 is too much for future proofing, especially when you dont need to future proof, because i cant think of any hi tech games due out in the next 2 years....and even if there is something, i bet the 7970 can still handle it.
e.g.....my rig is way too powerful for 1080p, plus it's a total waste of time OCing it to 4.4, i only ever use it a few hours a day, i use this one instead, it's just a giant 800 quid console


as it beasts everything maxxed out at 1900x1200.