I feared the worst when the best of was announced, but as it turns out it's a release by the label, not by the band.
The label are all shirty that Oasis aren't extending their contract with Sony so they're getting all they can out of them before their contract ends (probably onto their own label).
Noel has said in NME & a few other mags that they've got about 2 albums worth of stuff already written so I shouldn't think they'll be quitting anytime soon

I've hoped for a Noel Gallagher solo album for a while but I think the time has been and gone for that.