My gut tells me that had Kobe made it clear to Dwight that it will be his team right away, not after the 3-4 more years that Kobe wants to play and "show Howard how to win championships", it would've made a difference, even with D'Antoni as the coach.
That does not mean that L.A. would've been a lock for a championship, given D12's penchant for whining. But one does wonder what Jackson might have accomplished in ego management.
Even if Josh Smith goes to Houston, it would take an MVP coaching effort by McHale to get that squad through the first round, but in the long run, they have a 3-4 year window to win.
I think little to nothing happened in that meeting to push Dwight further away from the Lakers. There have been reports that during the meeting, D12 seemed detached and didn't make eye contact. That was taken by the Lakers' team as an indication that Dwight had already made up his mind that he was leaving.
Right after the season Dwight stated that he wanted to be where he could be happy. Playing under a crap coach like D'Antoni in a makeshift offense, alongside a demanding superstar who was desperate to win a championship (something I think Dwight wants, but only on his terms), in front of a fanbase that believes the team should always be competing for a ring, in a huge media center, were all reasons D12 could not be happy in L.A.
Dwight wants the easy route. That is his right, but winning a championship has rarely if ever been easy and with the Rockets, it's not going to be any easier. I agree with your assessment of the Rox chances this coming season. But one thing is certain, the expectations won't be as high and he will be playing for a coach who emphasize Dwight on offense.
It is hard for me to see him winning a championship with the Rox but it is also hard for me to see him caring all that much, as long as he isn't blamed for anything.