I believe there is still a sizeable market out there waiting for a full release. I know of at least one person, maybe two or three, in that category.
You know what would make it even more successful? Embedded advertising! Sort of like the way they named all the football stadiums in the USA after commercial corporations, Larian can do the same in BG III and rake in some extra cash. We could have the FedEx Sorcerous Sundries, the Hilton Keexie Tavern, and the Sachs Goldman Countinghouse. Just make some signs using a nice calligraphic font so they look appropriate for the medieval fantasy setting, and we are all set. Throw back a Coca Cola potion of invulnerability and jump right back into combat!