I've come around to the opinion that impeachment is political theatre which has been drafted and put into motion by Trump himself. The first part is simple cui bono. The impeachment hearings aren't heavily impacting Trump in the polls, are rallying his base, and are tanking Biden, who was one of his most threatening foes electorally. The timing is suspicious: right before an election year. It also lines up with some of Trump's earlier moves, like releasing the John Miller tape or picking a fight with the Pope, meant to strategically suck the oxygen out of the news cycle to weaken his adversary's media reach at critical moments.
Then there's the testimony. If my theory were true, then Trump would have sent State Department people who are loyal to him and directed them to both feed the media 'bombshell' lines that they could breathlessly report on while AT THE SAME TIME completely discrediting the investigation among his base and independents. So who is the star witness? Ambassador Gordon Sondland. Sondland is not part of the 'permanent government', he's a hotel mogul and political donor who was put into his position personally by Donald Trump. If you're looking for the profile of a guy who is personally loyal to Trump and willing to pull this off, you can't find a better candidate than this guy. And what has he done? He's fed the media lines about how there was a clear quid pro quo, going on and on about it, but once pressed on the issue he instantly folded and his argument collapsed to the open admission that his only source was 'his own presumption'. The other guy who testified, Ambassador Taylor, ultimately based everything he was saying on things told to him by Sondland. I wouldn't be surprised if the leaker was ordered by Trump himself to set this firestorm off.