yeah if you currently rock a 290, then i would probably wait yes.
Could be, not sure... But even then, it will be hbm2, with higher speeds and larger capacity, some tweeks will be made and most likely it will be huge improvement. Nvidia will squeeze the last drop of GDDR5 so amd need to step up with Greenland and basically outperform them... And now, that Radeon is separate from the CPU division, we may very well see some revitalization of the GPUs... It's been a long time since AMD had the single GPU king of performance...
Unless you've got money to blow just get a good used 290x. Someone here on the forums may even have one you can get a deal on.