Graphics Graphics Upgrade Advice



I am currently looking to upgrade my graphics cards. The current system configuration is:
Intel i7 980X
Asus Rampage Extreme III
24GB Samsung RAM
Corsair HX1000 PSU
2x EVGA 670 cheesecake

I am going to be moving the two 670s to a secondary PC, and so I am looking for an upgrade to my primary desktop. I was thinking a pair of EVGA 970 FTWs. It is used for gaming, fps/simulation/strategy, and some video encoding. I will not even consider AMD cards (had one before, never again).

Should I consider holding off until the next generation of Nvidia cards come out?

Is the age of the motherboard going to hold back any GPU upgrade?

Is there anything else I should consider, before purchasing?