My thoughts:
Chrysler: Kill the Aspen, Pacifica, Sebring. Then build Pablo's Imperial CTS slayer. build all new Sebring that doesn't look like something out of AMC's mid 60's design studio.
Dodge: Kill the Nitro. Bring the Durango and Dakota down in size a bit no matter what the focus groups say. redesign the Avenger and Charger. Build a neon replacement. You can't kill the Durango and Dakota, they sell too well around here.
Jeep: Kill the 2 obvious suspects. Keep the Patriot. Keep the rest. Build new smaller V8 powered CJ7 sized off roader, the JK is a little on the big side. Build the Wrangler JT. Redesign the Libby again and bring it back to it's original specs if not appearance.
Plymouth: Bring it back!!!!!! With focus on MPG and/or basic transportation. Throw in a performance car (Road Runner?).
Engines: Stay away from hybrids and ethanol, and focus on squeezing more MPG from it's engine line-up. Ethanol is nothing more than a political vote-buying effort by the idiots running for Pres. and it's driving up food prices as well.