Due to different facts, age 35 should be considered old. But in a situation where a player deem it fit to keep having fun, there is no problem with that. He/she can then play more than 35 years. Not as if 35 years is the cap, but it is base on observation.
One thing struck my mind again, after a player might have hit 35 and above, you will see him/her struggling to get a club that will sign him or struggle for playing time.