Based on the interview articles that I've been reading, and also his blog - John Mayer is not a blues guy, his a pop guy with blues influences. So his main music will most probably still be within the realm of pop, not that there is anything wrong with that, with some hints of blues. From time to time, he will probably lash out with some TRIOesque album, but that will be in a 1 blues : 4 pop ratio.