But Sony is going to release a FF mirrorless.
Full Frame and mirrorless don't go together. An 85mm lens on an APS-C and a 135mm lens on FF have the same Field Of View. One of the BIG selling points of mirrorless is small & light. Hanging a BIGGER FF lens on a smaller mirrorless body kills that advantage.
1. EF 85mm f/1.8 USM - Max. Diameter x Length, Weight 3.0" x 2.8", 15.0 oz. / 75.0 x 71.5mm, 425g
2. EF 135mm f/2L USM - Max. Diameter x Length, Weight 3.2" x 4.4", 1.7 lbs. / 82.5 x 112.0mm, 750g
BTW not everyone wants/needs paper-thin DOF. For my advertising work I shoot a 5D3 at f/8 to f/16.
BTW2 This is where advertising is headed ... shallow DOF need not apply http://nitrogr.am/blog/armani-instagram-ads/