I agree - Detroit is more likely than either to win a series against the Spurs. Sheed does a better job than anyone on Duncan, and they have the playoff experience and poise to grind it out.
I expect Boston to unravel in a later 7 game series this playoffs. I'm not sure they'll make it past Detroit, for example.
L.A. looks dominant now because they're playing weak teams, and almost exclusively at home. And they have a weak schedule so they'll wind up with a good seed, but that won't mean much because all 8 teams are talented and capable of beating each other at least once or twice. I fully expect Kobe's injury to hurt him a lot more than he lets on, and that the gruel of the playoffs will be too much for him. And even if Bynum comes back, I don't expect he'll make much of a difference this season. Gasol is good, but not that good, and always gets exposed in the playoffs.
So, I think we're just as likely to see any of the other teams in the WCF as we are the Lakers.