snaq - first of all, great to see you here. it's been a while - at least for someone like me who doesn't follow the community thread.
anyway - obviously no team can "force" a player to accept a sign and trade. it's his option to accept it or not.
thing is, in today's nba, very few teams are usually under the salary cap in a specific off season - meaning very few teams are able to offer a free agent more than the mle.
on top of that, due to conflicting agendas, or a specific position already being filled, it is very likely that some if not most of the teams who are under the cap won't have interest in a specific free agent.
for example - look at next summer and who's going to be under the cap.
clippers
bobcats
sixers
maybe wizards
right there you can see that artest's chances of landing more than an mle contract are extremely slim.
i would say that only the clippers are a remote possiblity, and all things considerred - that's extremely low odds.
so if i'm artest and i want to get a new contract for more than the mle - even if i want to go to a contending team, i NEED the king's help, and my agent will try to orchestrate a sign and trade to one of the teams that i'd like to play for.
assuming that there will be at least one such offer (from ny) and probably more, why would artest chose the lakers ?
i dont' think he will.
he'd like to play here, but there are several other places he'd like to play in, and if there's such a huge difference in money - he's accepting the sign and trade for sure.
so realisticaly - if the lakers want artest, it is my opinion that they'd STILL have to deal with sacramento for him. still have the same problems of the kings being reluctant to help the lakers when no one is forcing their hand, and we'll still have to give up value for artest - only we wont' have kwame's expiring contract to use - and that contract could be the foundation for a current deal - with either a pick or a young player being the insentive.
if we do trade for him now, i think he can sign an extention right away - kind of like kg did with boston - but maybe lakerfan10700 (sorry, i know i allways mess up your numbers dude

) can quote you the exact rule from the f.a.q.
if we don't extend him, there's very little danger in doing that.
it may even be the smarter move - because of the scenario i discribed up top of artest's options in the offseason.
- assuming we'll want to keep him and the only offers he'll have are mle offers, we can be fairly confident that keeping him is entirely up to us - even though he'll be unrestricted.
we just need to offer more than the mle, and combined with the good situation which apparently he wants to be part of - we should be able to keep him.
so if i understood your question correctly, and you're worried about trading for him now and then losing him next summer -
i think it's safe to assume that would be entirely up to us if it happend.
so much so that i'm not even sure we should extend him right now even if it is allowed (as i said - i think it is, but only 98% sure).
the point i was trying to make is that "simply picking him up for the mle next summer as a free agent" may prove to impossible, and we'll once again find ourselves having to negotiate with the kings and even be in a less favorable position than we are now imo.