Geek Jed :
Oh really, you mean in like 5 months, for a game, I'll have to buy new hardware?
No. Without more of an idea of what you want out of your gpu we can't say what's overkill.
Do you want to play all games at ultra settings or are you happy to reduce settings?
What Hz monitor will you be using?
What resolution will you be gaming at?
For example 1440p at 60fps and high to ultra settings you only need 1 980Ti, however 4k at 60fps and high to ultra settings will require 2 but if you played at 4k 40fps and medium settings you could get away with 1.
Also buying 2 cards now for £1200 and using them for 4 years may not be as good an option as buying 1 £600 card now, using for 2 years and then spending another £600 and using that card for a further 2 years, you can also sell your first card