http://www.blazersedge.com/2015/1/20/7864841/portland-trail-blazers-nicolas-batum-chris-kaman-tradesGo with your initial instinct, not your new one. Batum is slumping but he's familiar with the team, they're familiar with him, and you'll still have a hard time finding any single player to check off all the categories he covers on a given night. The bar for trading him is still high even if his stats aren't.
Getting specific, can you find a player who...
...doesn't need the ball to succeed?
...can hit a three when called upon?
...initiates the offense when there's too much pressure on your point guard?
...racks up 5 assists and 5 rebounds a night?
...moves without the ball?
...can defend the opponent's best wing?
...is still in his mid-20's?
...makes a reasonable salary?
I can name you a couple guys like that but you can't get them in trade. Everyone else outside those two will change the offense. That's permissible but better done in the off-season, not with a 32-11 record headed towards the playoffs.
If Batum continues to slump, if this isn't just another one of his up-and-down cycles, and if his poor play ends up costing the Blazers, the summer is long enough to entertain every trade suggestion known to man. He'll be in the last year of his contract, a prime candidate for moving if the Blazers aren't sure about keeping him. My guess is they're as sure as they ever were and will wait this out. If they weren't, why didn't we hear about a harder pursuit of Jeff Green? That move would have eased reliance on Nicolas. But Green is in Memphis and Batum still dominates the small forward spot for Portland.
As for causes, I'm loathe to speculate. As I just mentioned, it seems like we've had this kind of discussion for 6 years running. The dip is deeper this time, but Batum has always come out of it. I don't believe the mainstream chatter that this is entirely injury-related. His struggles started before his wrist got hurt. (Though injuries don't help, of course.) But absent input from Batum himself, we'd just be guessing. Speculation seldom turns out accurate, especially in complex, multi-threaded situations. At this point we should probably pass on the "Why?" and concentrate on "How long?" and "To what effect?" I'm willing to give Batum to the All-Star Break, at least, before trying to figure out definitive answers. Let's see if he's swung upwards by then.