They'd bring out a 2080 Ti Super to replace the regular 2080 Ti in order to avoid the 2080 Super eating into their top end card sales. If the gap between 2080Ti and 2080 Super becomes too narrow, the 2080 Super would eat into the market for the 2080Ti, so they have to expand the gap wide enough to still make the 2080 Ti SKU attractive to buyers. Hence the 2080 Ti Super, because NVIDIA is not only competing with AMD, but also itself when it comes to their card line-up. The profit margins at the high end are nothing to be sneezed at. Plus having yet another fastest gaming card will give them prestige in the eyes of some consumers (those who have to have the latest and greatest no matter the cost).