I don't really see what a Jiraiya Pain would bring to the table that hasn't already been brought. Jiraiya's trump abilities came from sage mode. Being that Jiraiya's dead, is he even still in contract with the frogs for him to summon them and have them draw sage energy while he fights? I don't really see how Jiraiya without sage mode is a worse opponent than god realm, unless you consider the emotional impact it'll have on Naruto.