When I was running my photo business (2007 to 2011), my standard cameras were originally a couple of Pentaxes, but then I moved to the Panasonic L1s, Olympus E-1 and E-5, then a Panasonic Lumix G1. Then, as I wound down the business, I bought an Olympus E-M1 when it came out in 2013. And I just ordered a Panasonic GX9 body to take advantage of the latest sensors and the GX9 body form factor.
I made and sold thousands of prints, licensed hundreds of sets of images, and exhibited extensively during that period of time—usually winning various awards and recognitions at every exhibit I entered.
FourThirds SLRs and then Micro-FourThirds mirrorless cameras did a superb job as professional photographic equipment: it proved reliable and produced high quality photographs. The Olympus high grade and pro class lenses are as good as lenses get, the Panasonic/Leica lenses are similarly excellent, and the ultra-fast Voigtländer mFT lenses are outstanding quality across the board.
So whatever is happening with Olympus is a question mark, but Panasonic is still delivering new cameras and new lenses, and the community of pros who use FourThirds format continue to produce excellent work with their equipment.
Is it going away? I don't know and I don't care. My E-1 (first actuation in 2003) is still going strong, my E-M1 is as new, and the new Panasonic GX9 is a beauty. My lens kit is complete and outstanding. All this stuff will make photographs for as long as I want to shoot with it.
I shoot more with my Leica CL (APS-C) and Hasselblad 907x/CFVII 50c (33x44 medium format digital) now, but that's for aesthetic reasons and for reason of what lenses and accessories I have for them more than anything else. I know that I get excellent results out of all of this equipment, and that the bottom line isn't the equipment: it's the photographer.
G
Equipment is transitory. Photographs endure.