It's a sad thought that they would even do an 8th, although I think Paul would've wanted his friends/co-actors to go forth without him. He sounded like he meant to retire soon, anyhow. But the loss of someone so essential to the storyline is not only devastating but makes for a huge hole in the family. And I can't see why they'd WANT to come back, either. Furious 7 ended it beautifully. Sometimes you just have to leave on a high note.