So hot prediction: the game isn't going to be any not microtransactioned then it is currently. Books will still be a thing. The PHB, DMG, and MM will be complete books. Supplements will still be regularly printed. D&D Beyond will still sell books piecemeal if you want. The only microtransactions I could see are additional D&DB supplements (like the Vecna Dossier of the supplement monsters for SJ and DL) or a return to web enhancements (additional encounters, maybe a new monster or spell) nothing that will make content useless.
The VTT is a different beast, but I think they are going to make their money selling us visuals rather than content. Spell effects, outfit styles, glowly weapon effects. Dice and character sheet frames, etc. You'll still need to buy the content for the VTT, but they are going to get you on making the experience very pretty. One need only look at how MTG Arena sells Magic on effects, avatars, alt card art and card backs ("sleeves") to see that in play. Add in those fomo content drops (fight Vecna! This week only! Earn a special visual effect for winning! Only $2.99)
What I don't see is a book like Tasha's chopped up, sold in loot boxes, or similar. There will be no pay to win because you can't win against a live DM. But you can sell magic effects that come in different colors or purple skin for your tieflings on the VTT. And you can sell them extra stuff like they do now. And I see both of those being things down the road. But if you play using just your PHB, things won't change.