I have a Thunderbolt Display and am looking at buying a MacBook Retina. Is it possible to connect it to my Thunderbolt Display using the newly presented usb-c to thunderbolt 2 adapter?
Unfortunately, you cannot use your MacBook 12" with a Thunderbolt Display.
Per Apple Support, you need a Mac with a Thunderbolt connection in order to drive this display and the MacBook just doesn't have that capability
The Thunderbolt Display is more of a Thunderbolt hub with a display attached rather than a mini Display Port display with Thunderbolt compatability.
The port on the MacBook 12" (Early 2015) is USB C 3.1 only and no adapter will convert USB to TB.