With regards to the theories, that Partridge (or someone else we think is dead) will "come back alive" ...

In this seasons second episode, the responding police officer Sheridan informs Bertram, that they have found "one male D.O.A (dead on arrival) and Lisbon down". Unless he's simply lying, I cannot see him come back. 

I don't really think he's lying either. The way Bertram reacts all worried/suprised when he learns that it is Partridge suggest he is in on the conspiracy along with Partridge. Certainly, there is no suggestion that Sheridan is on the plot covering up the death of Partridge.