Was he fired? I don't recall. All I know is, he's with (VH frontman #2) Sammy Hagar now.
This is from Wilkipedia:
Anthony's future in Van Halen is uncertain as he recently revealed he only played on 3 tracks on the Van Halen III album and didn't play on any of the new songs for the The Best of Both Worlds compilation. Anthony also revealed he was only allowed to participate in the 2004 reunion tour if he signed a reduced royalties contract.
Mike spent the summer of 2006 touring as a member of "The Other Half" along with Sammy Hagar. They performed songs from both the Hagar and Roth eras of Van Halen. At the June 4th, 2006 show in Phoenix, AZ, for example, Mike sang Roth's vocal parts on Running with the Devil and Hagar sang Mike's backup harmonies.
On September 8th 2006, Eddie Van Halen announced that his son Wolfgang is now Van Halen's official bass player shortly afterwards stating he had no more hard feelings towards David Lee Roth and would be happy to 'play a few gigs' with him. On January 24, 2007 it was announced that Van Halen was reuniting for a tour with original frontman Roth and Wolfgang taking Anthony's place. Van Halen's publicist confirmed that Wolfgang will be the band's bass player for the 2007 tour, but only time will tell whether the fans will come to see the show without Mike.
In addition, on December 12, 2006 Guitarist magazine has 'officially confirmed that long-time VH bassist Michael Anthony has been ousted from the fold and [been] replaced by Wolfgang Van Halen, the 15 year old son of guitar wizard Edward.'
