This is pure speculation, but I suspect the IS binocular market is still alive and well.
- In August 2017, Canon released the 10/12/14x32 lineup of IS binoculars
- In January 2018, Fuji release the 12x28 compact IS binoculars
- In September 2019, Canon released the 8/10x20 lineup of compact IS binoculars
- In October 2019, Fuji released a new version of the 14x40 techno-stabi
- I've also noticed several companies releasing their own re-branded IS binoculars in the past year or two (Kite optics APC, Vixen IS, Opticron IS, Kenko VC Smart, Viking Scout IS)
Considering that the Canon 15x50 was first launched in 2002 (That's nearly two decades ago!), it certainly feels like there is a lot of recent activity happening. I think companies are starting recognize the value of image stabilized binoculars for consumers. However, as you've noted, there is a conspicuous gap in the availability of new, affordable (I’m looking at you, Zeiss 20x60), large aperture IS binoculars. Will we get a new set of 40mm+ Canon IS binoculars? Given their recent releases of the 8/10x20 binoculars, I have hopes that they're continuing to fill out their lineup. But for now I can only wait and dream .