No one can tell you how many years exactly. If you have RX 480 you are probably ready for VR not just high or ultra settings right now.
But i dont believe any one see future and know where gaming will be in 5, 10 or 50 years. For VR you are ready, you can run now on ultra and high FPS.
I would say if you are looking just FPS even on LOW resolution and details you are ready for next 10-20 years (IF your components last this long and if PC will be still a thing as they are now)
Also you will for sure be ready on high settings on next lets say 5 years
BUT If there is next technology of PCs and gaming in next month or year or so maby all PCs will be ready to upgrade hehe