I understand that their success is built on the STP name and they don't want to drop it and start over, but if this is actually a potential legal issue they might not have a choice.. Actually, the members of Creed found a new singer as well, and became Alter Bridge.
I know there's a difference in that STP will still be playing the old songs at shows, but with the new album and touring cycle coming up, they could change the name and play mainly songs from the album with Chester. The older songs would just have to be considered covers. The only thing is their career has been long so I'm sure they have a lot of "staple" songs that they can't just drop from their sets.
I don't know.. I think they need to either make the hard choice to change their band name, or decide to keep it (make Chester an offical member of STP...not STP with Chester) and deal with whatever Scott might do about it.