The short history of these types of processors tells us that at some point they will become outdated. Who would have thought that the s802 processor, only 3 or so years old, then state of the art, would not permit android to be updated beyond 4.4.2?
Who could have predicted that the kodi developers would only allow kodi 17 to run on android 5 (and hence processors that support that).
So the short answer is you can't predict the lifespan of a chip because you can't predict what developers (both application and operatibg system) are going to do yet and what underlying dependencies they are going to introduce.
Having said that, my old t8 running androud 4.4.2 and a kodi 17 compatible fork (cemc) still runs like a dream with anything i can throw at it.
One of the beauties of android apps is that there is better back compatibility with older os than say apples ios. Many apple apps no longer run on my old iphone 4 or have much reduced functionality.
