they should go back in time to warn them selves about the invasion then you have two bosses and two shaundis and two kinzies and two matts and all.getting back on topic here, i agree with both sides of this argument and have come up with this.
i like how saints row 4 sort of had you relive your past, but it was moderate and i really wanted to spend more time in those places.
So lets say somehow they slip into a different dimension with there awesome new space adventures, the only way to get back to their own dimension is to make things right in the other one.
this could open up opportunities to see more of what it was like back in the day and mayhaps even come to realize what all you have done and atone for it
idk just rambling
to fight against the aliens first you take out the aliens fighting the white house then you go around killing the aliens trying to invade steelport and stilwater and then take the fight to zinyak .
change the whole time line by getting the zin army on your side because you killed zinyak and you go break johnny gat out agian and you get the ships and you got the time machine again.
but sigh that means you would have never met cid after i think about it so hopefully they get him out.
i bet volition can't do a story like that because it would cost so much money and time to do two characters with two of the same voices because litery imagine how much time that would take for you to do two characters with the same voice its a nice thought .