Believe me when I say that being a professional online poker player is almost impossible today (at least if you live in a "first-world country") and will be even harder in the future with all RTA (Real Time Assistance), RTS (Real Time Solvers), and of course AI.
Online Tournaments will probably exist longer than cash but will be more for entertainment and in lottery-style formats like Hypers, KO, and Spins.
BUT you can still use online cash games to train your skills and use them at LIVE poker which is still soft in most places.
My prediction for the future is that
poker online will be more and more casino-like and the sites won't want winning players.
So play for fun and entertainment online and if you want to go pro and earn money you almost certainly have to play live.