What I'm hoping to see is a new penf. When it came out, they somehow managed to cram into that small body almost everything the em1 had at the time. The om3 is pretty small, too, but for some reason they decided to keep the faux-pentaprism bump. It would have been great if it had the viewfinder to the side.
But 100% agree on the OM-1 and OM-3. They're smaller than many APS-C bodies, especially once you add a lens, but they're nowhere near pocketable, not even in a jacket pocket. And I feel like the OM-3 was a bit of a miss - it should have been a "rangefinder" form factor (no pentaprism hump) and a few mm smaller in each dimension. And marketed as a Pen-F. That said, the camera itself seems to be pretty darn good - basically a slightly smaller, vintage-vibe OM-1. Once used examples hit the market, I'll be tempted to buy one.
My parents both shoot Nikon DSLRs and I chuckle every time they break out their birding lenses (400mm NIKKOR of some sort). It's as big as my forearm and fills half a backpack. My Lumix 100-300 (yeah, not quite apple-to-apple) is minuscule in comparison. [I don't do enough wildlife to bother with a more expensive telephoto).
There's Esquisse (https://esquisse.camera/) trying to step up, but it's still in the very early stages.