I'm thinking Launch Bay sticks around for a while, because the park still needs to:
Replace Mermaid
Replace BatB
Update Disney Jr.
Redevelop Echo Lake/ Replace Star Tours
Overhaul Fantasmic!
That's not to say that Launch Bay couldn't come before any of these, but Launch Bay also provides a nice (large) space to sell the merchandise and hold the meet 'n' greets that Imagineering wants to keep out of the land. I think it's going to become the Figment of Hollywood Studios (I.E., good enough for now).