Perhaps Town University's WTMD 89.7 The Breeze can fill the Modern Rock hole? They only posted a 0.5 share in the ratings, and their non-commercial. There little doubt that if they go Modern Rock their numbers will climb.
WZBA 100.7 would certainly make for a good candidate - they have a 1.9 in the ratings with their Classic Rock format. They're already doing some type of Rock, why not try Modern Rock?
Sports outlet WJZ 105.7 is down 3.1-2.6, and their cume is less than 250,000.
What about WFSI 107.9 Family Radio? Maybe they should make the move to Alternative?
That's 5 choices that we now know of where a station can go Modern Rock - WLZL, WTMD, WZBA, WJZ, and WFSI
WLZL, for all intents and purposes, is now a DC station. Even though the signal hits both Baltimore and DC, and actually covers Baltimore better, CBS has decided to target DC with it because that's where the money is. I don't think they would try to take on DC101 in DC, so this station is probably out.
WTMD, while not scoring big ratings, is trying to follow in the footsteps of successful non-comm AAA stations like WXPN. I don't think an all out flip would be appropriate, but it wouldn't be a bad idea to do a specialty show at night and an HD2 channel like XPN does.
WZBA- maybe. It's not the best signal to the south, which is why I think they're having problems with Classic Rock. If you're a Classic Rocker in, say, Columbia, you're just as likely to listen to WBIG. There's also some competition between WZBA and the 80's Rock-flavored WQSR and of course, WQSR has the better signal. Alternative would have similar problems vs. DC101 and 98 Rock, but it might work a little better than what they're doing now.
WJZ is low-rated but Sports is a huge moneymaker. They're not flipping anytime soon.
WFSI obviously isn't doing anything under its current ownership, but if they were sold, you never know. The negative is that the signal is similar to WLZL's, so whoever bought it would want to target DC more than Baltimore, and may not want to take on DC101.