I think your best bet for a $400 card would be... a high-end GTX 970? Namely, that one EVGA model that's selling for $390 on Newegg right now?
Or, if you're willing to put up with the heat generation and power consumption, you should totally go for the new revisions of the Sapphire R9 290X Tri-X OC on Newegg. Those are quite capable of outperforming the GTX 970, and they go for just about $315. Again, though, you have to put up with heat generation and power consumption.
In my opinion, the addition to the 980 Ti to Nvidia's lineup will just be filling a price point gap. They have no reason to change the prices because people interested in buying the 980 Ti probably won't be interested in spending less than $650, which is the most expensive *reasonable* 980 cards are right now. The only cards going for $700 or $800 that I'm familiar with are the EVGA Classified and Kingpin, respectively. But, come on. Looking at the specs, $230 more doesn't really justify LEDs on your card, nor does it justify a better silicon lottery unless you're a hardcore overclocker. I'm not into overclocking, though, so I'd much rather buy a GTX 980 Ti for $800 rather than a possibly overprice GTX 980. And if the GTX 980 Ti is closer to $750 or even $700, then that makes buying such an expensive 980 all the more questionable. So the GTX 980 Ti is probably going to fill the gap between normal GTX 980s and the Titan X, rather than shove cards out of the way like the 980 did to the 780 Ti.
Look on the red team's side of the house, though, and you might see such slashes in the R9 290X. The R9 390X is probably going to replace the R9 290X, after all. The only reason why they wouldn't deflate the R9 290X's prices when the R9 390X is released would be that they've already cut prices in half compared to what they were in Q3 2014. The cheapest R9 290X was about $500 back then, many good aftermarket models such as the Vapor-X approaching and even surpassing $600. Now they're between $330 and $300. Will AMD drop their prices even further, especially if the R9 390X sits at a higher price point? It's possible, but it could go either way.