Out of everything that has happened in the Trump presidency thus far, this is the most historic I'd say. The understaffed white house is historically unusual but that's more of a prelude to maybe something happening the future. The healthcare repeal would have been significant if it went through but it didn't. But this... its not analogous to anything else I think. Its not Watergate, because while he did just fire someone actively investigating him (way more highly placed than the official fired in Watergate), this guy actually deserved to be fired and would have been under anyone else. A closer analogy to me is the revelation that J. Edgar Hoover blackmailed presidents. But that whole scandal made very few outwardly visible waves. Comey... Comey may have actually decided who the president is. Opinion polls demonstrably tanked for Clinton when people heard about the reopened investigation, presumably afraid it would turn something up and they'd have buyers remorse. Now we learn a core fact used to justify reopening the investigation was a lie. Holy shit.
I don't know what's going to happen here, to be honest. All of recent history with the cabinet appointments and the senate investigations subcomittee suggests that Trump is going to try and put a personal supporter into the position and it might work. Maybe it doesn't and we get a headless FBI. What's going to happen to the investigation, what's going to happen to the FBI? What has the investigation even found? Things are happening so quickly and this is so unheard of. We're steering rudderless into unknown waters.
Edit: Also, Comey's name is mud and everyone is questioning him. If he abused his power in any other ways, we're likely to hear about it in the coming weeks. "We live in interesting times" someone who's a lot less frightened and angry than me would say.