Too many unknown
But what we can learn from history is that the RTX seem to be a breakthrough tech, and with any breakthrough tech, there are growing pains involved in the name of the early adopter tax, lackluster gaming support, and unoptimized driver. Knowing this, I took a plunge on a 1080ti recently after the mining craze has died down and pricing on gpu has stabilized again.
If you don't mind the hassle/risk involved in purchasing 2nd hand, wait until new card launched and people replace their old gpu with the newest one and the 2nd hand card flood the market.