Though there were promises that the band would continue, it looks like Plus 44 is done. Mark Hoppus spoke MTV about the project:

Since late August of last year, I've been in the studio every week writing songs with the intention of putting out a record of my own. As of this week, I've got about 10 songs in various stages of completion and another 10 ideas that I still want to work on Travis has played on a bunch of [my] tracks, and he's working on his own album as well. We totally support each other in whatever we're doing.

He's like a brother to me. I see him in our studio every week, and we'll be in the room of the studio he's working in, listening to stuff he's recorded, or he'll come into the room where I'm working and check out my songs. He's played on a bunch of them, and he's asked if I'll play on some of his songs. We collaborate and give each other ideas and support. That's what I meant when I said [in the interview at the Woodies], 'No matter what I work on, Travis will be a part of it.