Third parties will not be making onednd compatible material, but instead developing their own games/heartbreakers for a fairly niche audience.
Nope.
They're going to make D&D-compatible stuff, slap "5E" on the cover in a huge logo and "Compatible with the world's most popular role-playing game" or even "Compatible with Dungeons & Dragons".
They're just going to do it outside the OGL, and when WotC comes for them, there is just good outcome for WotC, because it will come down to copyright and trademark law, and WotC has a ton to lose on that front. Even if they cause one company to shut down or whatever, the case will define the limits and show others how to avoid that in future.
Medium term, it's a viable plan (even if cynical and soulless.)
I don't think it is, not if they want to keep growing.
That's the problem here.
1D&D was always going to lose customers.
All editions changes do when you're doing well/popular. Not just for D&D, but for everyone. You lose some amount of customers, and you hope to pick them up again over time. Sometimes that's quick, sometimes that's slow.
By their actions, WotC have drastically increased in the number of people they're going to lose in the 5E - 1D&D transition. If the push the VTT any harder than they already are, they lose even more people, because for a lifestyle-type D&D fans, the VTT is not of interest.
So it's not a viable plan when you include 1D&D in the mix at all. It's just stupidity, trying read anything into it is basically a kind of reverse conspiracy theory. Let's call it "Catfall theory" after the way cats look at you like they meant to do it after they fall off something.