Little more complicated than that in terms of the marriage. Sergio saw synergies that Daimler ignored/couldn't fathom. Chrysler has enormous engineering capabilities as well as large/SUV/truck experience. Fiat has enormous experience with small/midsize vehicles and commercial trucks. The sales areas around the world also didn't overlap.
Add that up with a lot of other things and you have more reasons than not to merge at that point. So far so good
Dodge isn't going anywhere.