GDDR6 starts production in Q1 2018, its on offer right now, but any real availability will be from Q1 2018, the next iteration of 16nm is also Q1 2018, so until they sort everything out and test it and announce it and make it available, etc... we are looking at a 2080 arriving in May at the earliest.
So it really depends what is "close enough" for you, you might end up waiting 6-7 months and stuck on your 290 or it may be 4 months from now. I mean it really depend on your definition and feeling of what is close enough. Ultimately unless you buy within the first 6 months of a new generation, there is always the looming thought of the next gen gpu coming along and you may end up never buying a GPU that way.
Personally for me I do not upgrade that often, but I always wait for a big change in technology, like going from GDDR3 to GDDR5, going from 28nm to 16/14nm, etc... those are the type of shifts that will provide immense performance improvement.