Stock suspension life question

I have a 2014 Sport, 4wd, 4 door long bed Tacoma with 135k miles. Tires are wearing perfectly evenly, ride is ok.

How long are the Bilstein shocks 'supposed' to last? And would I notice a difference if I replaced them with new Bilsteins?

FWIW, I swapped out the non-Bilstein suspension in my '07 4Runner with 120k miles with a new base suspension from an FJ and could tell a big difference in the ride.

 

my rears were toast at 130000km, fronts were fine but the coils were sagging. at 135000 miles your suspension is probably pretty tired.