Graves has been the "heel announcer" for his entire WWE run. Maybe they're trying to bring more heat to him, in order when he puts the heels over, he would bring them heat as well.
I don't really think it will lead to anything. Definately not a match and I don't really think there's a spot to have a Booker T match at Wrestlemania.
I would buy it as a real thing had Booker not be employed by the WWE, but he still is, isn't he? Tweets that management does not like get the boot quickly.