CPU upgrade in one year.

Probably not? Skylake was yesterday, Kabylake is sometime next year. It's possible that next year you'd want to wait for that, particularly as it's another "Tock" release so we can expect 5-10% IPC improvement rather than a "Tick" where we basically just expect a die shrink and better efficiency.

Unfortunately for LGA1150 users, the new 14nm -"lake" processors are going to use LGA1151 so you can't reuse your motherboard. And most are going to be DDR4, so you can't reuse your RAM either.

Odds are your best bet in a year is to pick up an i7-4790K, assuming you have a Z97 based motherboard, or a Z87 that can be flashed to support Devil's Canyon.
 
Ok here goes the speculation.
A year from now hopefully ddr4 prices continue to fall to make them competitive with how ddr3 is priced currently. This means going skylake won't cost much more than going devils canyon and will give you more performance.

If a new chip is not released before then, then going the i5 6600k would probably be the best bang for the buck, like the 4690k is now.

It is a moot question because any upgrade a year from now will be a new chipset, with ddr4. Which means new motherboard,ram and cpu. So there is no planning for the future.