Didn't they just redesign the Magnum???

They freshened up the front.

Magnum sales were soft after the first year, realistically it was really a niche vehicle in the current marketplace. Same thing with the PT vert, throw in the fact that it is built on a dead platform. The Pacifica never sold well either, and to be honest it never would have gotten better.
The Crossfire is gone because it'* a Mercedes. The new owners want nothing to do with Daimler anymore, and thank GOD for that. It'* a shame, I really liked the Crossfire, great looking car with some real nuts in the SRT version.