2.66 GHz over 10 years is better than 3.5 GHz over 5 years.
Ten years has the potential to see 5 Intel 'Tocks', so you'd have to be one dedicated person to hold onto a CPU that long. Besides, you'd be better looking at something along the lines of 3.2GHz (20x160Mhz) to support your 1600MHz RAM.
Back on topic. I've narrowed my choices down to an i3-4360 or an i5-4460. I'm currently leaning more towards the i3 at the moment because this way I can get a better motherboard, plus with a Z97/H97 board...
Better go with the i5 and a cheaper board. Unless you're going to OC, a H97 should suffice.
I can always upgrade to an i5 later.
Dunno how many times I've heard people say this, but yet it never happens. People invest the money upfront to begin with and by the time they have saved the cash/are looking to upgrade, they just buy a new platform again. With Intel changing sockets after every tick-tock cycle, it makes more sense to just buy the newer platform rather than purchasing that high spec CPU you were saving for. Go the better CPU now; it'll last longer and help negate the need to upgrade to a Broadwell (most 'ticks' aren't worth while if you already have the 'tock').
I'm curious about Z87 boards though. Is it possible they will work with Broadwell like the 9 series boards?
Nope, but Z87 can still be a good choice, if you don't need stuff like SATA Express. But going back to my previous statement, get what suits your budget now, rather than looking at something like the future Broadwell; it's not going to be leaps and bounds faster than Haswell and when the time comes and you're thinking about finally getting that Broadwell CPU, you probably will see it isn't worth it and will just wait for the next platform. Only thing to look out for is BIOS support of the Haswell refresh (if you go that path), but that G1.Sniper you posted already supports them.
EDIT: If anything, you could get a Z87 board now and pair with an i5, then pick up a cheap Haswell refresh i7 in the future (as, like I said, Broadwell won't be much faster), then wait it our for Skylake or beyond.