Yeah, that's very likely. Sony will be pushing the PS5 and they won't be supporting the PS4 with new exclusives. The next Uncharted almost certainly won't be on PS4. Same with the next God of War, the next Gran Turismo and others.
For you though, you could totally trade in/sell the PS4 Pro and recoup some of the cost once PS5 comes round. Pretty obvious, but worth mentioning. Haha. Or just wait for PS5, you’ll likely get 5 years out of it then. I guess you’re in 2019 camp so!