yeah. If AMD has a R9 390X which beats Titan-X by >10% then AMD will be in a good position to make some good margins. They desperately need it. Nvidia will be forced to adjust the prices to reflect the competitive situation.
It's safe to say, that whatever AMD releases, it won't top out at 12GB of RAM. Nvidia will not adjust the price of the Titan X, as it will still have a unique position in the market.
And give nVidia a target? don't think so.
What would be the point of NVidia leaving performance on the table? There's no downside to releasing the best you can produce at the time for your highend model, and realistically, any card at the top of the pile is going to be judged by its overclocked performance, anyway, not its stock clocks. If AMD doesn't want to set a target for Nvidia, they can just never release another product again.