For me, the main selling point of mirrorless cameras is the small size and weight. I see no advantage of a mirrorless camera for sports, BIF, etc, a DSLR would be better for these uses.
A small/light APS-C mirrorless camera using APS-C only lenses, from 20mm to 85mm would be perfect for PJ, street, editorial portrait and fashion, event and all around hand-held photography. To me it makes no sense to have a 12 Oz camera (a Sony NEX 7 weighs 10.3 Oz) and a 36.16 Oz EF 85mm f/1.2 lens, YMMV.