There are several reasons why the received wisdom about the speed of the Trump removal process may be completely wrong. Not surprisingly, most of the reasons relate as much to the political as to the legal context.
One: Perhaps most importantly, unlike in prior impeachment situations, even this early, almost everyone in Washington really wants Trump gone. There are literally only about 50 people for whom this is not true. The difference between the parties this year is that the Democrats are not upset when people figure it out, but the Republicans are terrified about their base doing so. (When the Republicans say they want to get all the facts out about malfeasance on their side, you know the subject of the investigation is in deep trouble.)
Two: A prima facie case of obstruction of justice by President Trump has already been made out, most of it from his own statements and admissions. This comes from his firing of Comey, his statement that he performed the firing because of his feelings about the Russia investigation, his statement to the Russians that he (and they) have gained from what he believed to be the successful firing. While that alone is probably enough, there will be plenty more. This could go to a grand jury very quickly.
Three: This time round, no one seems to be suggesting any barriers, such as Executive Privilege or National Security, to getting the information quickly. This is in very marked contrast to 1972 – 1974, when it took well over a year to resolve the barriers. I think the main reason is listed in number one above, that no one wants to protect Trump, it is just that one party does not want that fact to be too obvious. It is also partly that Trump has waived many of the legal issues by his tweeting and statements. I think it is less the reason for the absence of such privilege claims that the legal issues have already been resolved — US v. Nixon gave Nixon no outs, but clever lawyers have since then, with a sympathetic audience been able to find new arguments — it’s just that there is no such sympathetic audience outside the immediate Trump family and their hangers on.
Four: It really does not matter whether a President can be indicted or not. You just charge a conspiracy to obstruct justice, name the President as an un-indicted co-conspirator, and get all the information to Congress. This is what happened with Nixon, in that case with the permission of the judge overseeing the grand jury (the now largely forgotten hero John Sirica.)
Five: In today’s digital environment, not only is there additional evidence everywhere, but the process of finding and putting it in the right order will move much quicker. In the Watergate investigation it look months to get all the interlocking evidence hand typed onto sorted color-coded index cards. The timeline can be ready for grand jury presentation soon.
Six: If they can get rid of Trump, the Republicans want it done as fast as possible. This is because the other prong of the investigation, the one dealing with the underlying Russia collusion, is going to take much longer, but if successful, it is potentially much much more damaging to the legitimacy of Republican power. If by the time we get a new President it is clear that the Democrats should or might have won without the collusion, the pressure on Pence to offer the Vice Presidency to Tim Kaine will be immense, and we will be in a period of coalition government. If the Republicans do not accept something like this, they will be killed at the next election, whether midterms or the presidential. Even if they do accept it, much of their radical agenda is gone.
So, almost all the rational incentives align in the same direction.
The only questions are whether the Republicans can figure this out, and if the Democrats want and are able to, can figure out how to take advantage of the alignment.
Actually, the main reason I now think that impeachment is the more likely route is that Republicans do not have to be the ones obviously triggering the process, at least until very near the end of the game. In contrast, if they used the 25th Amendment, it would basically Republicans starting and managing the process.
But, that choice of remedy analysis assumes that new bombshell inherently destructive of Trump’s relationship with his core base comes out — and that might happen tomorrow at 5 PM. Tax returns, anyone.