Recently switched from SmartThings to Homeseer and was dreading losing the ability to automate my nest thermostats. However, I figured out that via the smartthings -> homeseer plugin I could still control my nest thermostats via SmartThings "scenes" (which I then "execute" in homeseer).
So for anyone out there wanting to automate your nest thermostats, you can do it via a SmartThings hub!