I'm with you here. I remember playing Everquest when it first launched and being amazed seeing people sell digital magical items on eBay for hundreds of dollars. Blockchain just takes out the middlemen and costs. Hive can make any in-game economy into a real world economy.
Rather than build from scratch, I think a Hive team could look at a partnership with an existing game or licensing software. Mindark and its Entropia platform have always come to mind.