Lets see, Aprilia bought Guzzi afew years ago. Has arguably brought them up to speed as for quality, name recognition, product diversity. Now Ducati is looking at buying Guzzi (again).
By my take Aprilia would sell MG only if they see it internally a a loss leader to be dumped, or the money offered by Ducati is so astronomical that they would be fools to pass it up. So if Aprilia keeps Guzzi its to loose money, but gain credit for the marque history; or they actually are making a good profit on the Guzzi line and won't sell unless the offering is going to be so high that Ducati won't see a profit in Guzzi for years to come.
I don't think Ducati will buy Guzzi to lose money, and (I have not studied the profit/loss statement for Aprilia) Aprilia is making a decent profit on the line as it stands. So this strikes me as a no smoke and no fire issue.