no, don't bother with SLI with the new 10 series cards, while some new games and applications can still take advantage of this they are few and far between, older games that could take full advantage of this will of course still do so but honestly, it's not worth the money. Just overclock your card and have fun. And also, there's not much in the way of "future proofing" your PC like that. I'd say look into selling it and investing the money gained from it and a little bit of the money you are already thinking of investing into another one and get a better 1080 with proper cooling solution on it and overclock that, or look into getting a 1080ti if it's within budget. But definitely just overclock and enjoy the extra performance.