Will assigned seats solve the Jetway Jesus and Freeloading Family problems?

My take is that preboarders will still preboard; it's a legal thing, so that continues, they'll just have to pay more for a prime seat, which is fair. The family who buys the cheap fares then whines to the captain about being separated even when they board last . . . that goes away; they sit in the seats they paid for. I recently had a captain say the following when a family boarded late: "We're not going anywhere until at least two people move so this family can sit together."