Some guys called Ukraine "de facto NATO member". And no, if the USA don't want to defend Kievan Nazies, they won't defend Estonian Nazies either, and some people believe that Putin already started "proxy aggression" against Estona.
Right now, Russian people in Narva (still, formally Estonia) unofficially declared "Narva People Republic" with the simbolic similar to those of Donetsk and Lugansk People Republics. So, right now Estonia (and NATO) face the nice choice: 1) They can agree with demands of equal rights and equal safety for Russians, and it, highly likely, will turn Estonia into another pro-Russian NATO member (like Hungary); 2) They can decide to escalate and send police to arrest those guys (or nazi thugs to kill them). Highly likely it will cause riots and further invasion of Russian Federation. 3) They can do nothing and wait, but highly likely, Russians will increase pressure.