This might seem like a good scenario for Miami, but the Dolphins would be better off giving additional picks than adding Crowder to any Boldin-trade-package (and that's even assuming that Arizona would want Crowder).
Sending Channing to AZ in a trade would create another hole to fill in the offseason. I know everyone here is quick to say "we'll just go after Dansby during free agency". That's a great idea, except in this coming uncapped year, a couple other suitors may very well come calling with a greater need at ILB/MLB than Miami has (not to mention a much fatter contract -- New York Giants or Washington anyone?). Miami thought they could land Calvin Pace, and probably Jason Brown & Bart Scott. Guess what? All three players followed the money. As much as Dansby professes his interest in playing for Miami (who wouldn't want to?), he may like an even bigger contract than we may be willing to offer.
My point is that to create another hole (that DEFINITELY needs to be addressed anyway) by trading Crowder is not a good idea at this point. If we send Channing away and Dansby follows the money, we may be left with Torbor and Ayodele as our only ILB options. We could try to fill those positions in the draft, but we also have issues with OLB, S, and NT to worry about as well. Keep Channing, and if you trade for Boldin, send them a 3rd/4th and other pick considerations (ex. future picks or conditional draft selections).
Side Note: Many posters here like to crucify Channing Crowder and make him out to be an idiot (despite the fact he acts like an *** from time to time). The reality is, for better or worse, he IS the best ILB we have on the team and performs at an average to above-average level of play. In short, he is solid. Pair him with an ILB that compliments his skills set, and Channings game may very well get better.