There is honestly no such thing as future proof. There is no way to tell if that i7 will make any difference at all in the future. It is very possible that games will use more cores vs. hyper threading in the future. It is generally never recommended to spend any real money trying to make things "future-proof" as it doesn't even really exist.
People though in 2009 that hyper threading would matter in games within 2 years and look, it still makes very little to no difference at all.
You are not understanding the point. Right now if you spend $320 you get a gtx770. You will not get more performance for that money when the new cards come out.
$320 is $320. You won't get magically more performance because the series is new. That is not how it works. Chances are you will have to spend MORE than $320 to get equal gtx770 performance due to the cards just releasing and being new. It is smarter to keep the 770.