magiklok :
Na I didn't buy, at least not yet. Been building my new pc with 780 still. I just want to know how long to wait lol, but there no way to tell it seems 😛
It just depends what you're doing.
If you're just gaming on a 1080p monitor then even a single 970 is going to run just about everything fine on whatever settings you want.
SLI/CrossfireX setups of modern top end cards will only even benefit you if you're needing to push 60fps+ on a 4k monitor, or 144fps on a 1440p one for super smoothness.
re:timelines - the 980ti/titan2 won't be coming out for a good while. After the AMD 300 series initial launches in the next few months. It's planned to still be on 28nm process.
the 300 series is supposed to begin coming out in march/april - the first big card launch is the 380X. (apparently on 20nm process, with 4gb HBM memory) big daddy 390X to follow (with factory water cooling like the 295x2) still in Q2, and then the dual gpu card 395x2 in q4 of 2015. (apparently at the same $1500 price point per card) The lower cards will probably not be using HBM, they will be redesigns on the previous architecture.
Nvidia isn't moving to HBM memory until Pascal hits in 2016. (they were developing HCM as a competitor but it fell behind, so they are going to AMD/Hynix joint project HBM next year) So the remaining Nvidia releases this year will all be using GDDR5.
So again - it all depends what your usage is going to be. Decide on your monitor setup and goals are, and then tailor your GPU configuration to it. (personally - I'm waiting for dual 395x2 cards for quad CrossfireX. Your goals may differ.)