I have a question on upgrading my GPU

StormFade

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Dec 25, 2013
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So currently my specs are:
Gigabyte Z87-HD3 Motherboard
EVGA Dual Classified GTX 770 4gb
Intel i7 4770k @ 4ghz OC
8 gb of ram
EVGA 750w G2 Powersupply
NZXT H440 Case
Samsung 840 evo 256gb
WD 2TB Green HDD

I was wondering if I should upgrade my GPU now to a 970/980 TI or wait until the next series of GPU's come out.

Note: I currently only game at 1080p and plan to upgrade to a 1440p by the end of the year.