I would hold off on expecting them to include all the Tasha's, Xanathar's and other new supplements right off. That should be saved to DLC because otherwise you're setting a moving goal post and making it really hard to finish development.
That depends on what the initial goals were and how much Larian knew about the plans for D&D when making them. For example Dragonborn have not been implemented yet anyway, so it would not be much more work to implement the new versions coming with Fizbans instead of the old ones, if they are implemented at all.
Also implementing new models and classes which came with new books is easier than implementing rules and mechanics changes like how Tasha made race completely irrelevant because everyone must be the same for reasons.
So there certainly will not be a blanked adoption of entire books, but who knows what parts Larian will pick up and what not.