j man has as much of a chance of coming back as orichimaru.
Jiraiya's dead. Suck it up, Believe it, and Accept it. Him coming back alive would undermine all those important flashbacks he had which, in Naruto terms, is indicative of an upcoming death.
there are 2 way we will be able to see jiraiya again
1: is in someone flash back on him
2: if someone use that one jutsu orochimaru used
other then that he is dead