i think suzuki would be a more likely candidate for vw, they have a car and motorbike arm, more akin to what vw are used to. and seeing as the models between suzuki cars and volkswagen dont really clash it could be a good mix for them.
fiat could if they decided to, spend the money on ducati and they already have several tie ins between alfa romeo, doing the 147 ducati, fiat doing the monster panda and of course ferari with ducati using their wind tunells and design help. whether fiat would want to tho now is another matter. they are currently the 3rd biggest automotive producer in the world and are busy reorganising chrysler, dodge and i think pontiac whom they have just taken controlling stakes in and preparing to relaunch fiat in the states either through attached dealerships or as rebadged dodges etc. remember fiat are acknowledged as the worl leaders in small automotive engines . this of course would leave the door open for piaggio makers of vespa etc, free to buy ducati but after their recent pusrchase of aprillia, i somehow cant see that happening, but then again piaggio are the third biggest two wheel producer in the world