I think it'll be a long, long time until electronic shutters will be a useful implementation in the medium format sector.
Electronic shutters almost always degrade the image quality, even though it's just a little bit - and electronic shutters introduce artefacts when confronted with movements - which is the reason why professional cameras are not equipped with electronic shutters, they have 'at best' hybrid shutters which are also necessary to protect the sensor from dust so it isn't exposed all the time (and if I remember correctly those cameras with hybrid shutters were primarily equipped with ccd sensors).
Of course those artefacts wouldn't be that visible at 1/8000 - but to be honest nobody really needs 1/8000 x-sync speed and I doubt anyone would want to pay extra for 1/8000 sync speed combined with artefacts when you use slower shutter speeds. Naturally you could use a leaf shutter lens as 1/1600 and below - but then what's the point of going below 1/1600? 1/1600 is plenty and that technology is already tested and proven.
The only real advantage is that electronic shutters have no moving parts, so basically they would last forever.