It's not out of realm of possibility, and it would be a serious provocation of that's the case. That said, this obviously doesn't change anything strategically, and I expect Russia will likely just ignore this. It's pretty clear that Russia has been dictating the pace of the war for a while now, and the fact that they haven't escalated yet indicates that they're content with the current state of things.
I imagine that Russia would prefer avoiding a direct conflict with NATO, and the war with the west is relegated to economic and geopolitical spheres instead. However, if Estonia is responsible for the strike that would indicate that at least some western countries are trying to provoke further escalation.
Exactly, Russia understands the reason for the provocations perfectly well and there's no reason for Russia to react to these provocations. And completely agree that Russia has lots of options for asymmetric response.