Kobe has won the Lakers more games than he has cost them, so switching him for Harden would be a net loss. The optimal situation for the Lakers is to have Kobe, but have him distribute more. Especially to the bigs who are playing great. None of this fixes the Lakers biggest problem right now, which is a weak bench and weak 3 point shooting. How far the Lakers go will depend on who they play in the playoffs. Favorable match ups could easily get them into the Conference Finals. Not sure they can beat OKC in a seven game series, but after seeing Duncan and Blair manhandle them in the post it is a possibility.
If you take Derrick Rose off the Bulls you have a defensive version of the Denver Nuggets, a loaded team with no superstar. I guess another fair comparison would be the '03-'05 Pistons. They would definitely miss Derrick Rose late in games. I don't think I would pick that team to beat Miami in a seven game series.