8.6 devices will only read "ThinOS" policy, and 9.x will only read "ThinOS 9" policies, so no they wont.
Hi, I am using a "root policy" for all my devices, mostly 3040s. Most of them are running 8.6_807/810. I did upgrade one of my device to the version 9.3.2102. My question is when I select my "root policy", I have the choice to modify Thin OS and Thin OS 9. If I modify the Thin OS 9, will this reboot all my device when I will click on the "save and publish" button? I mean all including 8.6 devices? Thanks a lot.  
Root policy for 8.6 and 9.x