I think we are going to see a long tail overlap with RKL and everything that comes after especially on the desktop, presuming it is the last stand for 14nm.
On the PC side, for the broad swath of normal users, RKL will simply be good enough. Since it has Xe graphics it should allow for Intel to support it for an extremely long with their driver packages going forward.
And when it comes down to it, neither Intel nor AMD has that much incentive to focus on desktop CPUs with cutting edge nodes going forward. The real money being on the server side and second to that having power efficiency for mobile. Desktop CPUs have to come in a distant 3rd. As others have well said above, the OEMS are building their desktops to handle 65W-95W CPUs. RKL allows them to just keep using the same components with regards to PSUs and the like. If the global silicon shortage continues (why won't it?) how long will we see these sold?
I am not saying there won't be ADL and follow on desktop releases chasing halo positions, I just expect that even a couple years from now Intel is still going to be selling the market a lot of RKL. Especially if it stays remotely performance per dollar competitive. Will we see a 14nm CPU that uses DDR5? Ha...