I took a look at the article (well I assume it was the same article since you didn't post a link).
https://www.nationalreview.com/corner/the-not-so-persuasive-sales-pitch-for-impeachment/
His argument isn't that the Democrats would "get everything they want" immediately after the impeachment. He is suggesting that the political fallout in the future (multiple republican congressmen face losing the 2020 senate election, the possibility of a divided republican party causing them to lose the 2020 presidental election) will result in the Democrats in control of both congress and the white house post-2020, allowing them to roll back Trump's actions.
So, his argument seem to be "put up with illegal activities because you get some benefit at the end".
To be honest, parts of it almost seem to be a parody of the republican talking points.