Buying 10x0 or 20x0 now?

Long term machine learning researcher but I have not used tensorflow nor other framework because n the past, I wrote all the NN programs from the bottom up by myself. I plan to use tensorflow and other frameworks for some projects.

On paper, 20x0 cards are better than 10x0 cards especially for doing AI related work due to more tensor cores. The issue is that there have been reports of 20x0 GPUs having high failure rate and a famous GPU manufacturer told me that they are still trying to figure out the cause of the large failure of 2080Ti. Because of this, I considered to get 1080Ti but they cost almost the same or even more expensive than the new 2080Ti. As for the 1070 vs 2070, the prices are similar. What suggestion do you have? Just get a cheap 1060 temporarily until the high failure issue of the 20x0 cards is solved?

Just go ahead and buy a 2080Ti, particularly if you are prepared to buy another card later anyway.
Even with those purported “high failure rates”, the probability of your new 2080Ti working just fine is still vastly overwhelming the chance of receiving a defective one.