One of the issues I see is that purely electronic versions at prices far less than the paper version tend to kill your distribution network. Case in point: comic books. Both DC and Marvel seem to have adopted a model where the electronic versions of their products are the same price OR MORE than buying them in the paper version largely because they want to preserve their FLCS network. This network is what gets most people INTO buying comics.
In the same way, your FLGS plays a large part in keeping the hobby alive in the long term, so you, as a corporation, have to be careful not to undercut your network. It is, also, why I make a point of buying local even if I can get it a bit cheaper online. I want the store to survive.
So, if WOTC starts selling the book for 30$ and the PDF for 10$, they might sell a LOT of PDFs, which will generate good revenue for them now, but when all the FLGS stores have shut down or don't carry their products anymore, they will hurt.
So, I would THINK they would want to sell the book 30$ and include a PDF for free with it. If you want JUST the PDF, then I would price it at 20$ to try and encourage people to buy the book.
Assuming, of course, that the suits at Hasbro let them sell PDFs of new items at all.