as a 1080ti owner, I wouldn't be interested in getting the 2080, if I didn't have a 1080ti and was coming from something older then maybe it would be a toss up between getting a 1080ti and a 2080, so as they are broadly similar prices, if its a consistent 10% faster plus has RTX and DLSS then it becomes a more interesting choice, if its slower than a 1080ti then thats a different choice entirely
IT's back down to reviews again. If it's that close in performance to the 1080ti then it will depend on how well it performs with Ray tracing and is DLSS going to be as good as it sounds.