The demand for this format is decreasing very sharply, and therefore it is quite difficult for us to develop completely new optics for this ecosystem,” he says.
“I think the Micro 4/3 has many advantages, especially its compactness. Personally, I really like this system. But currently, the trend is clearly in favor of full frame, alongside APS-C (which is also in decline, by the way).”
https://petapixel.com/2023/02/24/sigma-wont-make-new-lenses-for-micro-four-thirds-as-demand-dips/
Not like they were making many lenses for m43 anyways, but they are making APSC lenses that could be ported over, so that's a bit dissappointing if they won't do that anymore.
From Sigma's perspective, they have to decide whether they want to try to find opportunities to make money with a format that is incredibly mature and has an incredibly wide range of options all the way from Panasonic and OM Systems' incredible (and relatively reasonably-priced) offerings to countless smaller manufacturers making both AF and MF lenses, or do they concentrate on
completely new mounts that have limited options? As a Product Manager, I know what I'd do!
While it's arguable whether MFT is "dying", it is pretty obvious it's not
growing at the rate that the handful of relatively new FF formats are.

Sigma is making the right call here, but I don't think it says
anything about the long-term viability of MFT as a format.
True, but people are missing the point.
Sigma is the first that I know of to publicly leave MFT. yes, there are plenty of lenses for MFT, but that’s also not the point.
They're not "leaving" MFT. As the article says, they're just not developing
new lenses for it.
Panasonic will probably keep making MFT gear, but if JIP doesn’t care about growing MFT and is only in it for the short profit, then Panasonic will no longer have completion and that’s not good.
Why? Canon's system is completely closed - they don't have
any "competition"
within the system. OM System doesn't need Panasonic - they're competing most directly against Fuji, Canon and Nikon's APS-C offerings.
Semantics. No longer developing essentially means they have an exit strategy. That would be like Sony saying they are no longer developing MFT sensors, that would essentially be Sony leaving MFT.
Comparing this to Canon is definitely not the same thing. Third-party lens manufacturers would love to start making lenses for the Canon mount. Just like they’ve been trying to get into the Nikon Z mount for years.
What we have here is arguably the best third-party lens manufacture in the world not seeing opportunity in the MFT format. Huge difference.
Just to mention that the OM1 is based on a generally available Sony MFT sensor. Apart from the A7Siii and phones, it's the only Sony Quad Bayer fast readout stacked sensor on the market. The A7Siii doesn't make so much use of the fast readout. The OM1 only uses two of the four readout modes, so that could be interesting for the future.
While OMDS may have had to place a large first order to get the unit price they needed, Sony carried the upfront sensor design and manufacturing validation costs. There must be reasons why Sony chose to do that. It was Sony who decided on 20Mpix.
OMDS have stated that the OM1 attracted enough
new users that the additional high end lens sales were attractive in terms of additional profit (and presumably free cash flow).
In my view Olympus made a real mess of their product strategy, including the MFT lens standards. Compare that to Sony, who adopted a variant of the EF standard for E mount and license the standard to 3rd party lens manufacturers, reserving only TCs and the highest speed AF protocols for their own lenses. If you have a Metabones adapter, you get Dual IS on a Sony body with any modern EF lens, just like that.
MFT is a small enough and mature enough market without the added burden of two different approaches to Dual IS, AF, weather sealing at the mount, and TC compatibility. Since Olympus controlled the standard, we can surely blame them.
OMDS clearly have some challenges in terms of managing with limited resources, the hit they took in home market share on the transition from Olympus, and cash management expectations from JIP.
So far, they have a more robust business "feel" to me than Olympus did. Shame that marketing seem to have carried on the Olympus tendency to talk rubbish, but maybe we are now past that.
I've spent a lot more money on MFT kit over the last two years than the ten before that. No camera purchase decision is risk free, but I'm mostly liking what I see.
Andrew