his age is meaningless here- his reflexes have clearly slowed from 5 years ago, but he is still good enough to be a quality batsmen
he is still very very hungry to keep playing (and frequently talks about playing for multiples years, something Misbah has not done)
and with a possible Misbah retirement coming soon, no one will be pushing Younis out of the team
I think he comfortably has 2 years, so maybe 15-20 tests. Even as his abilities continue to deteriorate, I can still see him getting 6-8 centuries
40 centuries is on the cards!!