He's definitely mentioned before that a large portion of the player base is mobile, and with the aspect ratios of modern phones getting even wider (the Galaxy s20 clocks in at 20:9) the black bar problem has gotten even worse. Of course, this means that in two or three years he'll have to announce the move to ultra-widescreen since 16:9 will still have black bars on phones
I'm a little curious where you live if you're playing on a 16:10 PC. I haven't owned a 16:10 monitor in over a decade, and I'd assumed they'd become an endangered species since I've only seen 16:9 or ultrawide monitors in US stores and online storefronts for years. Do you work mainly on a laptop? I do recall seeing an article recently that 16:10 is making a comeback there.