Wouldn't Quadrophenia 2 just be Octophenia?

It's not often you find yourself agreeing wholeheartedly with The Who, but their reaction to the plans for a sequel to Quadrophenia are pretty much spot-on:

Pete Townshend and Roger Daltrey have denied involvement, calling the project "a blatant attempt to cash in".

In a strongly-worded statement, they said: "For the avoidance of doubt, this project isn't endorsed by The Who, Who Films, Universal or any of the other rights owners of the original."
Bill Curbishley, the band's manager who produced the original film, added: "Quadrophenia is a significant and influential film based on The Who's music, not some Carry On franchise.

"Any follow-up could only be made by the authors of the original and would need to be worthy of the name. This karaoke sequel announced recently would be totally ridiculous."

The filmmakers, though, think they've got this covered:

the follow-up would be set in the present day and based around events in the book To Be Someone, by Peter Meadows, which was inspired by the original movie.

His book picks up where the narrative of The Who's album (rather than the film) ends, following the hero, Jimmy, through the punk era as he becomes a drug dealing gangster.

Director Ray Burdis - who previously produced The Krays, starring Gary and Martin Kemp - claimed Townshend had given Meadows' book the seal of approval, suggesting this counted as an endorsement for his film.

Yes. That's exactly how that works.