Horrible idea for the Democrats. Nelson just got re-elected, Florida Democrats need that 6 years to build a bench, because they frankly don't have one right now.
This, but you're ignoring the one heavyweight on the FL bench: Charlie Crist. In a special Senate election he'd be the best nominee for either party given his name recognition.
If he even ran. He'd likely be peeved that the Democrats turned their back on him to push Nelson into the race. Plus, if I'm not mistaken Rick Scott could appoint whomever he wanted to Nelson's seat. He'd likely appoint a GOP Senator, and he's got a strong bench to pick from.