I think you have picked the potential synergies EB.
FIAT will probably hang in a bit longer, but they can't aford to be stuffed around by the US legal system. The Supreme Court challenges are basically a tactic to get the US Government to compensate some US pension/bond interests, to maintain the rights of US consumers to sue for injury or loss attributed to Chrysler products built and sold prior to Chapter 11, and to alter the ranking of certain creditors. The key to the actions is interpreting the legality of the use of funds voted by the Congress to bail out banks for the re-financing of a manufacturer. It has to be settled quickly because the GM re-financing funds come from the same source.
The FIAT buy out of GM Europe is a non starter, the German government having sellected Canadian parts and component giant Magna to partner in the Opel buy out. It seems that they will also get Vauxhall as part of the deal but that is a bit up in the air at present as Gordon Brown has other things on his mind.
FIAT's main reason for getting involved with Chrysler is the marketing and distridution clout it would give them in North and South America, and in a number of other places round the World.
For FIAT the jewel in the Chrysler product crown would seem to be Jeep, which would expand the market coverage and get FIAT into a lot of places they don't really have any penetration of at present.
Difficult to see much else except maybe Voyager that doesn't need redesign from the ground up and a completely new product philosophy. Certainly they would have the knowhow to push eco friendly small cars through the Chrysler plants, and with the FIAT leadership in production tooling, do it with a usefull saving in labour costs.
Two problems at the moment. FIAT have to do better relating to the US car market and manufacturing culture than Daimler Benz managed in the disastrous merger with Chrysler, and of course they can't stuff around in the US courts for too long.