Where these buildings two blocks south, they would have been protected by the Capitol Hill Historic District:
Map from the Capitol Hill Restoration Society website (PDF).
Ironically, DCmud states that part of the trade-off for these buildings' destruction would be that Dreyfus would pay for a study that could potentially lead to an expansion of the historic district (too late for these buildings, though). I stressed the potential aspect of this, because in recent years, we've seen attempts to establish historic districts fail as often as they have succeeded.
In the last week, fencing has gone up around the buildings (see pictures below). Take special note of the last photograph, which shows a large building in the alley, too large to call a carriage house. It appears to have been a light-industrial building of some sort (perhaps Richard Layman can chime in and give some more background about this building). Regardless, there are some solid structures that will be lost when they are finally torn down, to be replaced by something that I don't hesitate to say will likely not have any kind of the permanence many of these buildings have exhibited.
I've heard people argue that it's alright if we lose a historic building or two here and there. What's the big deal? DC has thousands of them! The benefits of increased density far outweigh the loss of historic residential stock.
But I have pointed out before on my old blog that we are constantly losing these old houses to neglect or, as Layman astutely points out, a malady he calls "blaming the building" (mentioned here as well). The chipping away of our historical housing stock is especially disturbing to me in neighborhoods where most of this housing still exists in contiguous blocks. Part of what makes Bloomingdale such a nice neighborhood architecturally is the fact that, block-by-block, the original houses are all still standing. Shaw, on the other hand, has many places (particularly along the streets that were decimated in the 1968 riots) where that continuity is interrupted by 'modern' public housing projects or commercial structures that stand out like sore thumbs in the streetscape.
Perhaps witnessing the loss of more old structures convinces people in neighborhoods to rally for historic district status. The residents of Barney Circle are leading the way. Hopefully more neighborhoods (like Eckington and Bloomingdale, Brookland and Chevy Chase) will take note of the potential losses and do what's necessary to keep their neighborhoods from being destroyed one house at a time.