It has not been determined how WWE will handle the situation. They could either try to work around her injury or have one of the other babyface Divas replace Menounos.
Menounos will continue to perform on Dancing With The Stars, which airs tonight. The fact that she's continuing on with DWTS seems to be an indication she'll still be able to appear at WrestleMania 29.
Reporter's Link:
100% LINK (PHOTOS): Maria Menounos In *HOT SPANDEX* Again! MUST-SEE ASS PIXXX!!!