Nothing is timeless, especially in pop culture and one day Mario will have to hang up his suspenders for good.
I don't think the franchise will ever die though.
If we talk about quality gaming (my opinion): the 2d Mario games are cheap knock offs of the 8 and 16 bit era. Which are much better games.
3d Mario on the other hand are much better, and I would compare Ratchet and Clank to 3d Mario over Little Big Planet.
Though anyone who says Ratchet and Clank isn't a quality series is just a Nintendo fanboy. It's not my type of game but for a series that has been around 17 years less than Mario and never been bundled with a console it is doing very well for itself.
This is only my opinion.