The two biggest questions you gotta ask are: (1) Can you resell the 770? (2) Do you need the extra performance or is the 770 satisfying you?
If you need more performance for the latest titles, sell the 770 and buy a $250 390. Your total out of pocket cost is very low. This allows you to get a lot more performance while you wait for 16nm cards to drop in price over the course of that generation. Then, when it comes time to upgrade, you just sell the 390 and keep going.
The other thing is, while I do believe we'll see nice gains in the $299+ segments, I have no such expectations for the $99-249 segments simply because during this generation, this was the worst market segment (750/750Ti/950/960/285/380/380X).
To put that in perspective, R9 390 ~ 290X and at 1080P, that's
77% more performance than a GTX960. Why does this matter? If 960's Pascal successor is 80-90% faster, that's only getting you barely more than 390 level of performance. Are you willing to wait until Q2-Q3 2016 for that? If you are happy with the performance of your current card, of course the longer you wait, the more you'll be able to get for your $$$ but at some point if the performance isn't satisfying you, you have to upgrade.
If you aren't going to sell the GTX770 to recoup the upgrading cost, I would wait to get a card 85-100% faster than a 770 (390 is about 64%). Otherwise, I think right now is not a bad time to sell the 770 and grab a $250 390.
This is totally wrong.
Chummy use your gtx770 till next year and buy a 250$ card that will be way faster.
DO not buy a 390.
It might take a while before a brand new $249 16nm card is
way faster though.
If NV doubles the performance of the $149 750Ti, that's only R9 380X, so the $150 segment is totally out.
If NV doubles the performance of the $199 GTX960, that's just 13% faster than an R9 390.
If NV drops GTX980 level of performance to $249 with a mid-range Pascal card, that's still just 11-15% faster than a 390. Not that exciting compared to GTX970/390, unless power consumption and the latest features are critical.
Moving forward, I expect the most exciting dGPU segments on the desktop from a performance point of view to be $299-650, nothing below at least not at MSRP. The sub-$300 segment nowadays is just bad value. There is a large chance that both NV/AMD will replicate the strategy since 2012 and split the next gen into two parts - 2016 will be cards 40-50% faster per segment, and then in 2017 another 30-40% faster, or something along those lines.
What i purchase next i want to keep for good time, maybe till 2018 which suposedly comes next gen consoles.
Next gen consoles are unlikely to come in 2018 for 2 big reasons. The first is that with slower pace of performance increases, it will take a while before Sony's PS5 could have 5-6X the GPU performance at an affordable price compared to PS4. Right now the $600 980Ti is 'only' 3X faster than the PS4's GPU. That means you need to increase performance another 50-100% on top of 980Ti and then make sure it costs $150 max to fit inside PS5. That's not happening in 2018.
The second reason is that game developers make the most $ towards the latter part of a console generation. When PS4 and XB1 have 150 million install-base, that's when they love the console generation the most. That's why I think it's more realistic to expect PS5/XB2 in 2019-2020, not 2018.
Finally, no matter what single GPU you buy today, it'll be outdated for PS5/XB2 level games in 2019-2025 so don't even bother thinking that far. The GPUs in those consoles will smash anything we have out today so there is no way to future-proof for that in 2015.