You can use the newer headsets on lower end hardware, you just have to run them at Rift resolution.
You may ask what the point is then? But you get the advantage of much reduced, even non-existent screen door effect, plus with the Quest 2 the ability to go completely wireless.
If you don't mind using a Facebook account, the Quest 2 is a massive upgrade from the Rift, with very similar controllers and is 100% compatible with your existing Rift and Steam VR software. Plus you get Robo Recall native Quest version for free, if you got Robo Recall free with your Rift. Add to that a library of completely stand alone games that you don't need a PC for anyway.