It's why Cain beat him out. He had all the advantages that Romney had including money all put together, but wasn't prolife and was on the record of supporting abortion. In a crowded field it pushed him into no-man's land. If you wanted a progressive member of the establishment, your man was Romney. If you wanted a prolifer - your man was Cain. When Cain dropped, it's why they eventually went to Santorum, not Perry.
A prolife Perry would have established himself as the anti-Romney back last July and stayed there.
Perry would not have stayed there, not because of abortion, but because he is a truly awful speaker. He lost steam because he sounded clueless, drunk, and forgot which three departments he wanted to cut in mid-sentence during a debate. It was only a matter of time before he would have imploded.