I'm a skeptic of all conspiracy theories. The more elaborate the conspiracy the more skeptical I become and I'm an ardent believer in Occam's razor. For your conspiracy theory to work. Thousands of people over all government institution have to work together to some nefarious goal. My view needs only 1 person doing something in accordance with the natural behavior of a FBI director.
It even falls flat on it's own merit. Comey succeeds in bringing down Hillary and Trump? Then what? that still doesn't brings him any closer to the Presidency. He wasn't nearly close enough in the line of succession.
It's not a conspiracy theory. I don't think the world works in conspiracies --- things just happen, and sometimes very small groups push viral changes. I didn't mention any conspiracy: I think Comey wanted to be president. That's my explanation for his efforts to destroy BOTH candidates for president. I think he WAS the most dangerous man in America, briefly: now he's about the most distrusted, so maybe he's defanged; I hope so.
You shouldn't think in terms of line of succession! No coup every followed the legal line of succession: if they did, we wouldn't call it a coup. We'd call it, you know, succession. The junior military officers that take over everywhere everywhen right back to the Hittites are never in the line of succession: that's sort of the point. They don't have a chance to rule, so they take over as soon as they do.
A whole lot of people have no concept that real change can possibly occur. Certainly not in America!! And yet huge changes and break-ups of national entities happen continually all over the world and happened in America several times already, and almost happened more than that. I call this the five-minute belief system: the world will always remain as it is this five minutes. Weather, politics, crime, worldly goods, everything. It will always stay the same as this five minutes.
It never does, though. There is a lot more play in reality than in human minds