They would have to be cautious to remove more parking from that area, to build over an existing lot.
YC has 630 rooms right now. BC is 583.
This propaganda discusses the YC convention center expansion:
https://www.disneymeetings.com/blog...-center-at-disney-s-yacht-beach-club-resorts/. They tout 1,190 guest rooms, so I think they are leaving out suites at both resorts in their count. Dunno. The math doesn't work out for me.
But when you're trying to land 5,000-7,500 attendee conferences, even assuming 1/3 stay off site, you need to be able to offer a substantial number of guarantee rooms near the center (so, mostly YC/BC/BWI, with a possibility of Swolphin thrown in). Assume most will be either single or double occupancy for attendee occupancy. Offer some attendee busing from a few other resorts to hit some guarantee numbers, like they do for Gartner IT (which also books Contemporary, GF, Poly, AKL and Coronado).
Converting, say, 250 rooms at YC to villas seriously mucks with your guarantees and RFP offerings.
(Arguably, when BC and YC are occupied with decent convention occupancy, it reduces load on Stormalong Bay for much of the day. Conventioneers gotta convene.)