The Android phones I had so far never got anything beyond 3 or 4 years. I have an Apple 7plus that's turning 7 this year and pretty sure that won't be the end of it. It still gets regular security updates. As in every other week.
When iPhone started, it only got two years of updates. Then some got 2, 3, 4 or 5 years of updates. Android is fundamentally different and has to support thousands of devices, if a manufacturer is still giving 5 years of guaranteed updates, it's great, and this will only get better with time.