They're riding a good wave of buzz right now and outside of this forum the response to Solara has been lukewarm ranging to mild interest. IMO Silvery's a way better track and it's going to generate some good buzz for the band. Music video should be out closer to the song's release than Solara's was, so that will help.
New album in November according to that BBC broadcast.
D'Arcy coming back is wishful thinking unless Bill swallows his pride. James alone being a part of this again is giving the performances and songs the kick in the ass they've needed for a long time and it's a promising start.
In terms of popularity it's never going to be 1995 again, and that's not happening for any active rock band, but they could easily get up to Foo Fighters levels of respectable concert attendances and output if they just keep their shit together, play the hits and Bill doesn't force people to sit through entire new records live again.