The problem with this in my opinion is that these kids are going to be in colege too early. Hell, some if not most people at 17-18 don't know what to do 5 yrs from now, let alone for the rest of their life.
Thats why, in all honesty, I think they should still have gr 13. But actually make it count. I'm lucky enough that I do know what I want. I'm lucky that I am mature and am looking toward my future, but I know many who don't have a clue what they want to do. I think removing gr 12 would make that situation even worse. I don't know if this all works differently in the States, but I'm just going off of how it is here and what I think.