5e was designed as a "semi-evergeen" edition, and it is not going to leave us anytime soon. My suspicion is that it will last at least as long as 3.x, possibly longer, and will eventually have things like the Player's Handbook II, Monster Manual II (they can't hide them behind cute names forever!) and such, as well as sourcebooks which will be a bit less necessary to have (Guildmaster's Guide to Ravnica has already accomplished this). It too will lapse into redundancy, but I believe that it will remain much better balanced than 3.x and Pathfinder 1e ever were. A revised ranger will probably be released, along with new classes like the Artificer and Mystic, and other expansions yet undreamed of will follow for over a decade from now. At swome point, WotC might even do what they said they would, and incorporate fan-made homebrew content into official products (with some revision).
And, if you get tired of playing 5e, just switch to something else for a while. The next game I play with my home group is going to be Starfinder, Shadow of the Demon Lord, Exalted (yes, I finally tried it, and it isn't as bad as I thought), or Pathfinder 1e. The choice of which system depends on what my home group wants to play.