Based on these recent rumors regarding Tampa, I think the Kings would make better trade partners for them. Tampa is in their cup window and is desperate to make a trade now to make a playoff push. The Kings need a trade now to help them as well. Colorado, on the other hand, can take their sweet time into the off season and just push up the prices.
I am uncomfortable trading Muzzin or Martinez, but trading McNabb makes sense on a lot of levels. First, although he is not an elite or number 2 defenseman, I think based on his play here in LA, he is good enough to fetch a secondary scorer. Tampa is loaded with forwards and is willing to move one. McNabb will provide some stability to their defense, and with the rise of Forbort and Gravel, we really have no use for McNabb, considering we may lose him in the expansion draft anyways.
I wouldn't mind doing a McNabb for Boyle and 2nd round pick trade if one can be worked out. Boyle has the size to play LA style, would be perfect on the 3rd or 4th line, and has some offensive upside.