I highly doubt that Six Flags Over Georgia is on the table, and the same for Over Texas, though a Texas park would fit well for Cedar Fair. However, the only one I can fathom them picking up is Fiesta Texas (Since Over Texas is the original, Astroworld is such a dump), and it seems to do fairly well in the books so I'm not sure SF Inc. would part with it.
I think Six Flags New England could fit well too, being a park in the relatively un-corporate North East. However, if parks are sold, I think they will be split up among numerous buyers.