Matt's original statements are interesting but I do think they're flawed.
I think it's very reasonable to assume WOTC upper management has its eyes focused on digital. They spent $130 million dollars on D&D Beyond. I doubt the core RPG dev team has spent that kind of money over many years. No doubt they want to recoup that money through digital sales and we're seeing their experiments in that area with the Beyond-only sale of the Monstrous Compendium 4.
So that's to be expected.
I don't think the slower book release cycle is a problem. I think its intended. WOTC talked about how putting out too many big campaign adventures ensured that no one could play them all. They had multi-year adventures coming out every six months for a little while there. Now it's one big adventure a year (or so). This year has both Planescape and Phandelver and Below so those are two big ones within like a month of one another.
But I don't think that hurts D&D one way or the other.
One thing I've been thinking about a lot is what D&D does for the hobby and what we want it to do for the hobby. Branding is a big one. D&D branding brings people to D&D and people really into D&D try other things too. It grows the whole pie – rises all boats – and all your other favorite metaphors. Having a good on-ramp to the RPG hobby is important too. I think there is no more important product than the D&D Starter Set. Luckily, they've all been pretty solid. They at least don't seem to be getting in the way.
Solid core books is important after that to keep people in the hobby but after that, the determined DMs, they're out there googling things, watching the youtubes, and learning about other systems and other products and picking the ones they and their friends want to enjoy the hobby.
At least that's how I hope it's going.
I think we probably overweight the importance of WOTC's publishing schedule and published books other than the starter sets and the core books. Some people pay a lot of attention to them but others (I'd say about half) just start homebrewing their own worlds and many find other games they want to play instead.
So we'll see!