Shaq didn't go to LA because they were primed for a run, or because they had lots of cap space to build a team around him. They had just recently missed the playoffs, traded Vlade to get the rights to Kobe, and were definietly a team in transition from the glory years of the 80's. It was about the endorsements and about Jerry West and his ability to articulate his vision of how he was going to rebuild the Lakers.
As far as LeBron, why in the world would he consider the Knicks??? It will take years to get out of their mess. They would have had to start 1-2 years ago to get in a position to be able to have the situation ready for when LeBron is a FA, where they could build a contender. They are years away from doing that. They could have got out from under Francis' deal last after next year, but instead they took on Zach for 4 more years, and $60 million. The ability to move a player like Zach is easiest early or right before it expires, but invariably you have to take on more years when it is ready to expire. The chance of LeBron going to the Knicks is almost ZERO.