Its tough introducing a new camera system. Ask Canon when they released the EOS mount, Fuji with the X mount etc.
Mirrorless with its short flange distance gives many advantages when introducing a new system. Thus when MicroFourThirds came about adapters enabled lots of existing lens to be used while Olympus and Panasonic built out the range.
Leica, since they released the 35mm full frame SL have had a similar problem when introducing a new system, compounded by the fact that it is full frame thus most of the current crop of mirrorless lens are not suitable unless you want a crop.
We now have two zooms with the ranges 24-90mm and 90-280mm, and a 50mm Summilux prime. This year they intend to round out line-up with a 16-35mm zoom and three new smaller primes of 35mm, 75mm and 90mm.
Of course until then you can always use your M glass.