Needs hardware support, thus only works with RTX.
it will take a few years for support for raytracing to spread past the few AAA titles.
in the mean time, old 1080's can still push oldfashioned non-raytracing pixels just fine, as before.
Intel is plotting their own GPU, will that supprt RTX tech or something else?
AMD had hairworks, it looked nice, didn't really take up all that well. New AMD cards wont likely support RTX as such (Nvidia thing) and will most likely implement their own. Will differences on Nvidia/Intel/AMD implementations shatter the playfield where few games are X exclusive, some Y and some Z? possibly.
Will it all be "under the hood" in DirectX and game devs don't need to care? just click on "make pixels pretty checkbox" probably not.
Until actual release, benchmarks and other company solutions are reviewed, it's hard to make speculations. I would say that no, old fashioned cards are not out yet and can last the two to three years that it takes for RTX to spread. At that point, there will be new and shiny cards out there for picking.