5 years is par for the course actually. But a successor won't release before Q4 2019 at the earliest. Most likely 2020. In 2020, the PS4 will turn 7 years old, which is a decent life-cycle.
Is 5 years really par for the course for consoles? Maybe it just feels short cause there are consoles that have gone past their life cycle but I still enjoy (ps2, dreamcast, xbox, genesis). Ps4 has been out for 5 years and it still ain't shit
I still play PS3 games such as Gran Turismo 6, Final Fantasy XIII, SoulCalibur V, Mass Effect Trilogy, NieR, etc. And they've all held up beautifully. Well except for NieR, which unfortunately still looks like ass (great story though).