Apparently, since the "K" frame and the "L" frame are very close in size, and the "L" frame will stand up to unlimited Magnum ammo, S&W has decided to discontinue the "K" frame, and offer "K" frame-LIKE guns with the slightly beefier "L" frame.
I'm not sure what S&W will, or is going to do about the larger diameter "L" frame cylinder.
Possibly offer the new guns with a smaller diameter cylinder?
In any event, this is another step in S&W's move to simplify production, and hold prices down.