Man, BU admissions is tricky. Heres alot of text with no conclusive answers:
I'd assume that you're being considered for spots like everyone who interviewed from January onwards. So you effectively get a shot at the whole class. Whereas, I interviewed in early Jan and will only be considered this coming round.
Consider that BU interviews like 900 or so people and accepts 250 or so. (one in every three to four interviewees gets accepted). I wonder how many acceptances they need to give out to fill 1/3 of their class for pre-Jan interviewees. If they only give out one for every spot, then I'd say their acceptance rate should increase dramatically this round.
Therefore, your chances just got better. Unless they interviewed a ton more people this round. Then statistically your chances may have stayed the same.
If they are on top of their yield and know how many people will decline those January acceptances, then your chances are the same as they were before. They have to fill 2/3 of their class according to the information Dean Witzburg gave us, but 50 setas in the class go to combined programs at BU. So maybe its really only 1/3 of the class again up for grabs.
In any case i'd really like to go there and could live with a waitlist spot, they do have some movement.