Only if we're switching systems of government, which it looks like is entirely possible. You know, the earlier you can get them an indoctrinate them, the better. Plus it frees up both parents to be working.
My daughter took 2 years of Pre-K. I unfortunately had to work full time back then. She was only 3 the first year and couldn't get into the state program, but her daycare had a private Pre K they said she was advanced enough to enter. She learned a great deal there, and even started reading. Granted, she was read to at home and probably inherited the "smart" gene from my husband. The next year she was old enough for the state program and honestly learned nothing. The teacher even told me that she unfortunately didn't have the resources to foster the more advanced kids and recommended I enroll her in a private school the next year. I didn't for many reasons.
I think kids that young don't HAVE to be in school. When our educational system was actually good as a whole, most kids never went to school until first grade. My father started school when he was 7 and never understood why we want kids in school earlier and yet they learn less.
If parents pay attention to their kids, talk to them and involve them in mundane details, kids will learn. They want to. You don't have to buy "My Baby Can Read" or Baby Einstein. Just pointing to a picture of a cow and saying "cow," "moo," and spelling it out on a sheet of paper will teach a child.
For parents who have to work, the OPTION of sending their kids to Pre-K would be valueable. But other than that, I'm not for it. I think there are many other areas of education far more in need.