Im going to say that the Empire annihilates Earth. The only Marvel hero's that would be worth a damn are the ones that can fly and survive in space. This leaves only one to my knowledge...,Silver Surfer. Now, the comic Sufer may be able to dispatch the Empire fleet but we don't know much about the movie version. He was able to deflect a few rockets but thats about as much that we saw him do until he flew into galactus and then something happened. What happened when he flew into galactus...,fuk if we know. I'm going to say that ten star destroyers and an entire fleet of tie fightes and bombers will be able to remove surfer from his board easily.
As for the Phoneix, there is nothing to prove that she can survive without oxygen.
Xavier has never displayed psychic feats on a grand enough scale to even suggest that he can drop a star destroyer 😂 As for Cerebro, it was explained to be able to find anyone on EArth, not anyone in the galaxy. Besides, Xavier wouldn't even know who he is looking for.
Every other marvel hero will burn with the rest of humanity as the Star destroyers lay waste to Earth from a far distance until the Death Star is fully operational.
The only chance i see MArvel having here is if Surfer can transport Sue Storm and other heroes into space. Storm could create a barrier whilst Surfer carries them. Maybe a Sue Storm and a Nightcrawler would be enough to dismantle a Star Destroyer but i highly doubt it. I don't think Surfer would be able to Make it before being blow away.