They will try to sell things that people want. The horror.
They're still going to sell books and swag just like they do now. DndBeyond is already a subscription model with so-called microtransactions in the form of buying new content and customized dice or cool looking character sheets. I could potentially see some more options there, things like a customized character portrait generated by an AI or other things we haven't thought of yet. I don't see dramatic changes there though.
The VTT will be where they see the most opportunity to sell people small shiny bits. There will probably a free version, a subscription version, visual add-ons and map packs. Just like every other VTT out there. They've already stated that there will be map packs with assets (that you can reuse) for published modules. You'll likely be able to just purchase the map packs and assets without purchasing the module just like you can buy just parts of books on DDB now.
Most of the new revenue is going to be game adjacent with movies, toys, other related products. When it comes to the physical game product, I could see them giving people DDB with the physical product although how that would work is still open to speculation.