This week, Barron's has an article that indicates USG has little downside, a fair valuation of about $33 and possible revaluation to $38 in 2015 upon continued performance. That may help get it back into the $30s.
No near term buyout potential because Berkshire isn't selling and will not buy until they work through the NOLs. That means at least another 3-5 years before USG is on the auction block. But by then, it will probably be between 50 and 100, and possibly paying a dividend.