I'd say that although a Lady Gaga parody would fit well on the album, it wouldn't be out of the question for Al to not write one. The polka is pretty good material, but, many people apparently are looking forward to it.
"An eager nation waits while Weird Al ponders Gaga parody?" (a headline for an article I found on the internet a while back) Maybe Al can't avoid it. Of course, Al would have to try to find a topical subject that hasn't been touched by the "foul hands" of the millions of YouTube users.
Speaking of YouTube parodies, I'm pretty sure I saw a "California Gurls" parody there THE DAY THE ORIGINAL WAS RELEASED.
I've Seen Weird Al In Person:
8/26/08, 5/22/10, 7/15/10, 7/16/10, 7/17/10, 11/5/10, 9/22/11, 9/24/11, 9/25/11, 4/30/12