I'm pretty sure I read this reunion of Creed will not affect Alter Bridge in any way. Creed is supposed to do the album and then do a world tour and that's it. I think it's just a one off thing and then all AB members will focus back on AB.
Myles Kennedy is supposed to be putting out a solo record as well so all the AB members will stay busy for the next year and then come back back and record a new kick ass AB record.
Haven't heard the new Creed yet, but considering how good the last AB album was, I'm sure this will be good to.