My 2600k How Many Years Left

I'm just wondering how many years do I have left before I have to upgrade my rig I've been looking at Skylake and I've read a few comments that's slightly worse than Haswell and apparently Sandy Bridge was probably the best CPU they have released so far, For my own knowledge I haven't been keeping up on CPU's from INTEL or AMD heck even GPU's in a long time I seem to be losing interest in the field over the last year. I haven't got a proper gaming monitor at the moment currently us a old 17" TFT at max 1280x1024@60hz but I am looking at a nice 21" ACER monitor I play games like

Titanfall
Diablo 3
Farcry 3
BioShock Infinite

But I try to play on full well I can at the res I have on the current monitor I used to use a 32" HDTV TV via HDMI yeah not a gaming monitor but better res think I could get 1920x1080p@60hz I think ??? Bioshock Infinite would play at that res on nearly everything full. I was considering maybe just a RAM upgrade to 16GB for now but I may just save money for something else.

If I was you I would stay with Sandy Bridge until you have games that need more power.

When it doesn't work well for YOUR needs.

Skylake is better than haswell by a few percent.

I got a 2500k myself at 4.5Ghz. Personally it handles everything that I throw at it nicely. Games now adays are starting to use some HT so there is benefits of yours over mine. Overall though and I've gone back and forth over the last 3 years of upgrading... Ive still stuck it out. I've upgraded my GPU, I've upgraded my storage to SSD. That right there was worth more than a system update at the time. Also 8GB of ram will be more than fine in 99% of the games played these days. If there is anything holding you back its the monitor (1080p monitor would be great) and the Video card is getting a little dated but upgrading those 2 things the CPU will still be happy unless you are looking for the newer features on some of the newer CPU's/Motherboards.

If you do more than just gaming (video/photo editing) the newer CPU's will prove a little more useful, otherwise you are probably fine with the core system (mobo, ram, cpu) for some time to come unless there is a major break through.
Me personally... I might upgrade in the next 1-2 years, but my needs have been shifting so only time will tell if I will even go through with that.