Online games will be still when ps5 coming , so this nothing change , ps4 will be supported for many years , as ps3. Maybe today someone cheat in battlefield 1, b4 etc. but you cant say anything , because jailbreak not exist , in theory.
As someone said earlier , the question is when will release. I was talking with some active person from ps2 scene and he confirm , scene now is "dirty" , and if they do not release , remember this not a fear of sony!