That's a legitimate shame for open standards. M43 has its proponents and critics, but either way it is rare to see a somewhat successful multi-vendor standard in photography that actually worked . The main problem is that the market itself has been shrinking, and there's just not enough room to have so much competition (Olympus, Panasonic, Sony, Fuji, Canon, and Nikon). M43 was successful, but it succeeded in an area…
At this point M43 is, in my neck of the woods, basically a video format anyway. I do on-site videography (my schtick being "we can run a four-camera live show from anywhere I've got Ethernet and power") and all my cameras are M43 because they hit a great spot on the price/quality curve. (Sony's APS-C cameras are very respectable too, but the glass is pricey.) Never used an Olympus, never understood the point of one.…
That all sounds big until you realize an a7 body is like minimum $1000.