I don't see him joining the Lakers with Lebron there , kinda like Kawhi ,  Giannis is more his own man and not wanting to play second fiddle and under shawdow of Lebron s ever present demanding thumb  to rule the team from GM on down.  I expect he ll give the bucks ONE new contract and see how that goes down.   
If Lebron fades enough ,  it might be enough to put the Bucks over the faker town .
Kawhi , PG.  Giannis and Tatum have time on their side .   Lebron does not .  If Lebron looks finished , perhaps AD leaves to join the Bucks .