I think the Rebels are probably goneski forever. I don't think there's quite enough goodwill or opportunity for continuity attached to the brand to make a return workable outside a maybe a one-off farewell against the BILs made up of former types that will still be in and around Super next season: but far more likely to be the Drua, or Pacific Barbarians type of side that takes it's place.
Short term, I think RA, RV and Vic Government probably need to pull heads together and try to get a representative side and a colts into either the Queensland or ACT competitions for the life of the existing Super agreement, or the pathways completely collapse.
As long as the pathways are in place, and there can be "something" of good vibes around Victorian Rugby, I think there's almost certainly an opportunity for a different Melbourne based side to come into whatever is after Super Rugby.