Addendum…
Players on the island would level through BGs.
Heirloom gear would be purchasable on the island, but at a significant markup from the gear available to full sub paying customers.
Unrestrict players on the island from the limitation of the current trial system, so they have access to chat, mail, auction house and so on.
Blizzard could sell tokens to the F2P players who could then buy gear and consumables.