I think the 2080ti is overpriced in the current climate, and the 2080 offers pretty much zero reason to upgrade from a 1080ti... However... Nvidia have the market share and power to have RTX / DLSS features pushed into games enmasse to sell their products, so with that said, i wouldnt buy a 2080ti or a 2080 right now, but wait it out til enough titles are on the market or a particular title you want is on the market before switching, or your going to end up with disappointment.
Once DLSS is enabled i expect these cards to fly, however i did not on DF's review they reckon Maxwell was capable of some of the DLSS type stuff? Ask Vega owners how they feel about buying a card based on features that never got utilised, however with Nvidia you can rest assured these features will get rammed into everything at the detriment of previous generations, Nvidia want you to buy their products, so they will make sure there is enough use of the features to warrant it.
If i owned a 1080ti right now, id sit tight on that til DLSS becomes mainstream then move across, by then 7nm Nvidia will probably be on the horizon too. Right now your just paying early adopter tax for little more than a shiney cooler on the 2080.