The last time she played the area was at Iota in 2005. I don't think her popularity has grown by leaps and bounds since then.
I guess your statement holds true technically, but Arlington is close enough, right?
I don't think the club is generally responsible for picking opening acts unless they are someone local, am I wrong?
Well, last time she was in D.C. (AFAIK), she opened for Tricky. (This was circa 2001.)
So she could conceivably be booked as a strong opener with someone else headlining.