I have had the Loxia 35 and 50 for a few weeks now. I must say that I am not really missing using my M lenses on the A7s, as the user experience with the Loxia surpasses M lens use on the A7 (M's still are amazing, and obviously prefered for RF use and for use with multiple systems)...
The 50 is a jewel, tiny,and the 35 is no slouch. I suspect an 85 mm and a 21 or 25 mm lens would be the next options...I would be happy with a 21 and 85 and call it a day, seriously....A7s(II) and A7r(II) with silent shutters and IBIS would just about do it....optically, size, compactness, etc....
HEre is one from the 35 Loxia at ISO12800.....f/2...incredible that we can get these shots now!