We shouldn't worry too much about the future of D&D, but maybe WotC should worry about itself. There is something strange. Avalon Hill, what now is going to publish the new edition of Hero Quest, is in this time a separate company. Hasbro has licenced important franchises (little pony, transformers, power rangers and g.i.joe) to other company and not WotC.
I am afraid WotC is "burn", has suffered a serious wear, lost a lot of prestige by fault of the last controversies.
This company may become an important rival, and it is good for us, but I think Paizo is closer to become the number one. Months ago I bought the Spanish translated version of Changeling: the Dreaming 20 Anniversary, Starfinder Pact Worlds and Xanathar Guide. With the same prize the other publishers gave me books with more pages. I love 5th Ed, but the books of 3.5 had got more things, more complete.
I have said the weak point of d20 system is to be universal genre with the right power level. A new d20 Modern but to be totally compatible with D&D isn't so easy. Hasbro knows D&D/d20 may become one of the best cash-cows of the videogame industry.
In the past I liked to speculate about the future of the entertainment companies, for example the next acquisition by Disney or Hasbro, but we know the world economy has changed totally by fault of the epidemic, and the next year will show us a lot of radical changes, and not about economy.
And I don't wish to cause troubles, but we know in the entertainment industry some things aren't wellcome, for example lots of players didn't want soldier76 after Blizzard said he was... and this is only an example, but we also know lots of the fandom didn't like too much the last Star Wars trilogy. They have forgotten to be enoughly ideological neutral and they are suffering the consequences. In the business world you never can take opposite the clients if you want her to keep buying your products.