Magento 2 Access
This site Magento 2 Demo With Access To The Back End Admin is offering exactly that.
If you’re interested in Magento 2 and it’s developments then take a look at what they’re doing.
Of course Magento 2 is now live and people are actively using it for their eCommerce developments. If you’ve not got an installation of Magento 2 on a server then this site is pretty useful to see if the functionality is offering what you want.
Looking pretty good to me.