I think the 2080 will trade blows with the 1080ti making it a poor prospect when it comes to price/performance. The RTX features are nice but i don't think they will be implemented in enough games to make the purchase worthwhile for another year at least.
There's always going to be a premium for brand new tech, that's a given. Plus we're in a situation where Nvidia and the board partners have a ton of Pascal cards sitting around that they want to shift, so that will skew things also. Definitely not a year before the 20xx series actually starts to see some impressive implementation of RTX features though. A year is an absolute age in tech terms, and we'll be hearing about new GPUs by then lol!
It's not as though the 1080Ti is suddenly going to become a junk worthless GPU as of next week though!