Nationalizing Starlink involves paying the current stockholders what it's worth.

After nationalizing, Musk will have a huge pile of cash. He can then self-fund a new SpaceX/Starlink.

Yes, many current SpaceX/Starlink employees will stay put, but I'll bet that a critical mass will say "We get a fresh start on everything? I'm in."

We already have NASA.

Serious question - could they actually nationalize starlink? Suppose starlink takes their C&C keys and builds a control center in some other country. What does the US government do?