Sigma currently markets 16mm, 30mm, and 56mm lenses in MFT format (multiply by 2 to get the equivalent focal lengths) that are reasonably priced and have gotten stellar reviews. According to what I've read, Sigma has no plans to discontinue them, at least not at present, but it's undeniable that MFT's future is uncertain. After the recent changes at Olympus the only brand that still stands firmly behind the format is Panasonic and that is unlikely to change in the near future due to the popularity of such cameras as the Lumix GH6. Even Panasonic, however, is moving increasingly toward the full frame format and may eventually fully commit to it.
Right now I'm very happy with my Lumix G9 - the MFT format works extremely well for me and I honestly don't think it deserves the lack of popularity it now suffers - and have no plans to abandon it. I don't know, though, if it would be wise to continue to purchase additional lenses and accessories for it when the format's future is so uncertain