I don't know if someone else has already opened an issue about this or if it's already a work in progress, but I would really like to see OpenID implemented in Magento2 for the backend users. I'm not entirely sure if it would also be a good idea for frontend users but for the backend it would help a lot. For example for big agencies making a Magento Webpage for a Client. It is easier for employees to use their existing OpenIDs on every project. No need to have a centralized password database. Everyone knows their logins and it simply works. I would really like that.
Apart from that I really like how Magento2 is coming along and hope it's released soonish