According to The Wrestling Observer, while the WrestleMania 30 card is definitely beginning to take shape, with only a few weeks left until the big event, much of the card is still up in the air.
At this point it looks like the show will be an eight match card spanning the course of 4 hours.
Coming out of the Smackdown tapings this week, it seems as if The Usos will be defending the tag titles against The Real Americans and Curtis Axel and Ryback. This would mean Rybaxel would have to be removed from the Andre battle royal match.
As for The Shield, they are currently scheduled to compete in a 6 man tag team match against Kane and The New Age Outlaws. Tag Team plans have been changing a lot lately, however, The Outlaws have expressed interest in working with The Shield prior to their break up, so it's likely that match will happen sooner rather than later.
Previous creative plans called for Luke Harper and Erick Rowan to work with The Shield in some capacity at 'Mania, but with the 6 man tag match being planned for The Shield, it's likely Rowan and Harper's 'Mania participation will be limited to however they might get involved in the John Cena vs Bray Wyatt match.