As a Laker fan, the notion of Kobe playing with the Celtics is an absolutely abhorrent one that would cause me to tear my eyes out and remove everything green from my household. If it happened in real life though, I'd probably hate Kobe with a virulence that dwarfs anything that I could imagine hating Paul Pierce and his wheelchair for. He definitely would have played for the Celtics, and played for them with pride though; hey, if Paul Pierce who grew up only a stones throw away from the Great WEstern Forum played all these years for the Celtics, then Kobe would as well.
As for how it would play out, its still a stretch that they would have drafted Kobe 9th, as High Schoolers were unproven commodities.
The Spurs drafting Tim Duncan was an anamoly, which only happened after David Robinson missed the entire season and then they decided to tank the season.
Even if the Celtics do suck for the 96-97 season, which they still would in any case, its still a hard chance that they would get the Number 1 pick overall. Obviously, if the Celtics pick Duncan and pair him with Kobe, if you put a good coach around them then you're in business. They'd probably make the playoffs in the 97-98 season and get a hard lesson on the intensity of playoff basketball, but assuming that the Celtics can draft and sign good supporting players around them (like keeping Fox after 96-97), drafting a decent pg that can hit the 3, Kobe and Duncan is a very viable potential dynasty in the making.
However, if Boston doesn't get the Number 1 pick, it could end up drafting the likes of Keith Van Horn, as aside from Duncan, (and T-Mac, but he probably wouldn't be selected since the Celtics would already have Kobe) the 97-98 draft wasn't particularly strong. Chauncey Billups could work and you'd have a very strong backcourt (IOTL, he was actually considered a dissappointment at first and would need some maturing).
As for the Lakers, they would still be a pretty good team with Eddie Jones as your two guard with Nick Van Exel (who unfortunately was a nutcase). With Jones though, half the time you're not sure that he had a pulse. Assuming that the Lakers get Phil by 2000, there's still a decent chance that the Lakers could win that year with Shaq paired with Jones or an equivalent 2 guard, but they're not winning in 2001 or 2002 without Kobe. The Lakers also got Rick Fox before the 97-98 season, which meant they would have been starting Ceballos in 96-97, who was a 20ppg scorer (but unfortunately had that jet ski incident in 96 which made him a dead man walking before that 96-97 season). He was probably gone in any case, since Ceballos would have clogged the lane for Shaq, so yeah, they probably still trade him for Horry or the appropriate equivalent. Larry Johnson would have had to have been acquired from the Knicks, so it would have been Anthony Mason from the Hornets, whose pretty much the same though in terms of being a tough but undersized PF.
Personally, what I think might have been cool is that in 96, after drafting KG the previous year, the T-Wolves pair him with Kobe instead of head-case Stephon Marbury, so you end up with two guys straight out of HS who are ultra-competitive, gym rats, starting a long playoff run. I'm of the opinion that Kobe and KG would have really gotten along. Plus as an added bonus, Kevin Harlan probably sticks around as the local broadcaster for the Wolves.