How long could a Zombie Apocalypse seriously last?

[phinch1]

Andrespetmonkey said:

Runners (28 days, Dawn ot D remake) = until they starve.
Shamblers (TWD, Night ot living dead) = few months maybe. Maybe a couple years until completely eradicated.

There not zombies, they are not the living dead, they are humans that cannot be reasoned with as they are consumed with rage and just want to kill, ....they don't eat people