However, GTX2080 to Titan X had 30% gap, and Titan X became the next 1080ti with a new faster Titan Xp. Here the RTX Titan is barely 3% faster than the 2080ti. Chopping the RTX Titan you go nowhere.
Actually the difference in performance between the RTX Titan and 2080 Ti when comparing like to like is about 12%.
Having said that actually using the cards it is hard to notice the difference without running FRAPS.
It would be a pointless exercise for NVidia to release a 2080 Ti Super as the cards would still be quite expensive and the increase in performance could not justify this.
One hidden cost for NVidia in launching such a card would be the loss of somewhere to use failed TU102 chips that did not make the grade for full fat use.