They'll remain dark, with obviously a few tests until they find a new buyer. Radio Disney has always taken their stations dark when selling them. They usually sign on for a few test broadcasts to keep the license alive and then sign back off again.
Nothing on a buyer yet. There are options:
Entercom (There's been rumors of Entercom wanting to expand their sports stuff. That is the LAST thing we need in this market. WOKY is doing terrible right now. Insult to a station like WOKY)
Clear Channel (They have room for 1 more AM I believe. If they wanted to move the Sports format to 1640 and bring another format to 920, then that could be an option for them. Right now, it's not doing very good in the ratings on 920, and 1640, having been a Radio Disney station for 11 years would be a good place to try to get things going if they are serious about this sports format.)
Karmazin (Well, WRRD 1510 is a daytimer. Would be a nice 24/7 spot for his brownie points that he gets for running ESPN Deportes) And since it's owned by the same people ABC/Disney, he might be the first choice. That said, we'd see 1510 up for sale if he doesn't decide to put another format there. Really all Karmazin does is sports, except in Beaver Dam and a WHQG clone in Janesville (WWHG)
Family Radio (Family Radio has been selling off a lot of their FM signals. WMWK recently applied for a main studio waiver, meaning it will likely be sold off. To replace these FM signals, they have been buying AM signals.)
Wisconsin Public Radio (They could put The Ideas Network on 1640, and bring News & Classical into the market on 90.7, although this is unlikely. The closest News & Classical affiliate is WGTD Kenosha, but it does not cover Milwaukee County)
You might also watch for an LMA with the option to buy, which anybody could do. In this case, ABC/Disney continues to own the station, but someone else handles the operations and programming. This is what they did for a year with 1500 in Zion (A former Radio Disney station) until they found a buyer in 2002, not long after they bought WKSH.