Personally I think attempting to impeach Trump any time in the foreseeable future would be a bad idea, for at least three reasons:
1. He's still extremely popular with voters across large sections of the USA. The swing against Trump and the Republicans in the mid-term elections was modest, and there are still plenty who buy into his version of populism. Any attempt to remove him would mobilise supporters across the country as he goes on a Twitter bender.
2. There's no realistic prospect that two-thirds of the Senate would vote to get rid of him. Republican Senators would only need to see how much voter support Trump has to know that voting him out of office would see the end of their own careers, and the Tea Party pretty much take over the Republican Party.
3. Removing Trump would make Pence the President. On the grounds that it's better to be led by a scoundrel than a fanatic, I think a lot of Democrats might look back fondly on a Trump Presidency in comparison with Pence. Based on an article I've read in the "New Yorker" magazine, Pence is a dangerously ambitious Christian extremist who is pretty much in the pocket of the Koch brothers.
The article suggested that research funded by the Koch brothers confirmed that populist anger with the wealthy elite of the USA (of which the Koch brothers are notable examples) is a major force on both sides of American politics, but the intriguing part of the article was the suggestion that the Koch brothers were attempting to co-opt that populism for their own ends. Thus, the ironic situation that Republican populists voting for Trump are effectively supporting a shadowy political movement controlled by the very people they despise, and which is determined to act for the benefit of that elite, not the populists who voted for them.
In this regard I can see some similarities between Trump and, of all people, Hugo Chavez of Venezuela: Chavez gained power because of his ability to mobilise the masses with promises of improving their circumstances, but was maintained in power by a rich elite who had no intention of giving up their wealth to help the poor, and when the poor complained about Chavez's failure to deliver on his promises he simply blamed the middle class (and the USA). Likewise, sadly, I can see people continuing to vote for Trump even as his administration makes life tougher for them while the elite get richer, and Trump will get away with it by blaming Democrats and the Chinese.
What's the solution? I don't know. Maybe the Democrats need to embrace Bernie Sanders's style of Democrat populism.
But in the meantime, let Mueller get on with his work and concentrate on creating an optimistic alternative to Trump.