Okay, I just called the Sacramento OSO.
He gave me very straightforward answers, and was extremely helpful. You do not HAVE to enlist, but it can perhaps help your chances getting in. There is still NO guarantee though.
Even if it might help you, if you still have a 2.1 GPA and a 1010 combined score with, and no involvement in school or community you still most likely won't get in.
From my own personal experience talking to people from the Boat School, and the NROTC application, it seems these guys weigh leadership ability more so than grades. President of clubs or school, Captain of sports, Varsity athletics, community service, etc
I can't apply for the PLC until I'm actually enrolled in the college is what he said. I think that sounds right, and I think I read it on this site before.
You need a minimum 2.0 GPA, and 1000 combined SAT with reading and math. Average GPA is 3.0 he said.
Alright I still got like 8 months before I am eligible to apply.
Edit: When that Srg calls me asking to set up that meeting on Sat @ 3, I'll get this straightened out. I'll ask him why recruiters are saying I have to enlist to go to PLC, when OSO's say different. I'll ask him if this is just an attempt to lure more people to fill quotas, or for recruiters to boost their numbers. If this is just a plan to raise the number of Marines by 20,000. Think he will get mad? Well I don't really care if he does, it's an honest question, and for something as big as the Marine Corps, these people really need to be giving honest answers.