He fits big parts of the criteria. That he’s a comedian (more or less) as well as a singer make for a winning combination. There are huge problems, though. He’s mostly a voice actor with limited live experience. He hosted the season opener of Saturday Night Live this year and that went well but that just about it (oh and there was an aborted variety show, which isn’t helpful).
My big problem is that I think these hosts need to be movie stars. His voice became a movie star this year (in Ted), but so much of MacFarlanes comedy comes from being derisive of movies and movie stars, regardless of whether or not they deserve it. Making him the host of the biggest movie awards show of the year doesn’t fit for me.