While it still wouldn't be definite, if Disney ends up supporting HD-DVD the war may be over. However, if Disney chooses Blu-ray well then that'll solidify Blu-ray in the marketplace for many years to come.
Largest studios:
1. Columbia (with recent MGM purchase)
2. Warner
3. Disney
All of the other studios are a good deal smaller in movie catalog size and thus, there will be less consequences in their decisions of which format to support.