Personally I think they'll kick it back to the states to haggle over since all those reps and senators and the V.P. sent the brief to them. That way each individual state can make their own rules as they go and that would split the issue several ways just like it is now. since D.C. is not a state, and I think that would be their argument, I don't think it would amount to a hill of beans to them.
I think the folks in D.C. need to push the issue to get the law overturned. Had they been thinking they possibly could have possibly stopped it immediately after it was implemented by large demonstrations. (And I do mean Large) That's gonna be an uphill battle now.