Bird, you start with your opinion that we are at best a 30 win team, and repeat it as a fact. That's obviously far from a known at this point.
And, of course, no one would argue that Lebron James wouldn't make this team better. You could literally replace him with any player in the league and he would make that team better.
So, while, sure, you're right that having Lebron James instead of Rajon Rondo would make us considerably better, your point seems kind of empty.