There are some major unknowns here, but my theory about Comey is as follows:

1. He knew that the Democrats rigged the primary against Bernie, using a variety of methods. The most damning evidence that the primary was rigged is statistical, see Election Justice USA for a detailed report that was headed up by a past president of the American Statistical Association. Then check out the work of Bev Harris on the GEMS election-tally software and how it has been rigged since at least 2004.

2. Comey believed, along with nearly everyone in media and government, that Hillary was well ahead of Trump and would win. I don't need to source that claim, but if you want to read a reasonably good report on how the polling went so wrong, see Nate Silver's blog. Comey also knew that Hillary had the means to rig the election if she got into trouble. This is important. When he made his July announcement, and again when he sent his letter to Congress in October, he was betting that the Democrats would stay in power no matter how badly the public reacted to his statements. Prosecuting Hillary was a practical impossibility, and personal suicide for Comey given what she would do to him once she was in office.

3. The Democrats did in fact rig the election, but they did it so late (starting about 9 pm Eastern on election day) that it wasn't enough to keep Trump out. See Bev Harris discussing this with Alex Jones the next night. She mentioned specific Democrat-controlled cities that were very late in reporting, presumably because they were "adjusting" the totals using the GEMS software. What is especially suspicious is the way that data from Milwaukee was handled in the Wisconsin recount. Harris specifically mentioned Milwaukee as one of the cities that took forever to report. During the recount, the rest of Wisconsin was more or less done, with minimal changes; yet as the deadline approached, Milwaukee was going slower and slower, and the interim hand-count totals were tens of thousands of votes out of line with the numbers generated by GEMS. (See Heavy.com coverage of the recount.)

4. This was a result of panic and poor planning. Wisconsin was not a good state to rig because it had physical ballots. To rig it was dangerous; to rig it and then LOSE was disastrous. I don't know what Jill Stein believed or knew when she picked Wisconsin for her recount, but it was like flicking on a light and seeing cockroaches scatter. The only solution was to drag out the Milwaukee hand recount so that it wasn't finished by the deadline; then the secretary of state would be forced to use the original GEMS-adjusted numbers, and certify that the election had not been tampered with. See the work of Richard Charnin for more on all these issues.

5. Incredibly, absolutely no one in the establishment media had any concerns about the recount being manipulated in this way. Less incredibly, the Trump administration didn't object either. I know for certain that they are aware of GEMS because Roger Stone has written about it. My guess is that it is like the firing of Comey and many other aspects of draining the swamp; they aren't raising hell about it because they're not ready to do so. (There are some internal frictions as well, since many staffers aren't Trump loyalists and would leak anything they said even in a closed meeting.)

6. Firing Comey is the best evidence we have seen since the inauguration that Trump and Sessions really will go all the way. It will be incredibly traumatic and chaotic to prosecute half of Washington, but in the end I think they will do it. I don't want to try and guess who will actually get convicted or what sentence they will get. Once the arrests begin in earnest, there will be a lot of deal-making. Comey might manage to skate, simply by trading on what he knows. I'm not saying he should skate, simply that in a gigantic case of this kind, prosecutors are going to have to make deals.

Bottom line: This was like the starting gun for the next phase of the battle. Expect a lot of people to start positioning themselves to minimize damage to themselves, rather than protecting the pedocracy. They'll keep up the Russia narrative and the "White House is in chaos" narrative, but only a few really deranged people like Keith Olbermann believe it. From here onward, the timetable will be set by Trump, Sessions, Rosenstein, and whoever the new FBI Director is.