Given that Sony is revamping their ps4, it seems that they want to stick to the 8 year lifecycle of consoles

Er.

https://en.wikipedia.org/wiki/PlayStation_4

The console was released on November 15, 2013

That was less than 3 years ago. The next console is due out in 18 months, at the latest. That is not an 8 year schedule.

building a top end computer now, will easily carry you to the end of this gen.

Building a mid range rig would do that.

Sony has already altered its contracts with the games developers to reflect the upcoming machine. Development companies are now required to provide what is essentially two version of their games. One for the PS4, and one with upgraded visuals for the PS4.5. That means anything you buy now should be using the specs of the new console as an absolute base level for component choices.

Do you really think anything below a GTX 980 is going to cut it in 5 years if you want to stay in high settings territory? Given how fucking notoriously shitty PC ports are? Not a god damn chance.

It depends on what OP wants in that time span.

I would guess that he'll want to not have a shit experience, nor to have to keep shelling out money for no good reason.

I think it would be better to just worry about this console gen

This is wrong for the reasons I explained above.

Get a good CPU, a good motherboard, and a top end GPU. My original advice was to wait for the new GPU releases in order to get a better grasp of where the market is heading, how fast, and at what cost. New high end GPU's may be roughly the same price as current high ends, but with vastly more staying power.

If that's too much, then the cost of current high ends will fall, making the purchase a lot more palatable, and less costly, all without sacrificing too much in the way of longevity.