Sure, the Republicans are going to fight against a second Impeachment, but there are two possible resolutions:
First: They agree and we get Trump removed from ever holding office again. We set the standard for the future that a President doesn’t get a break from encouraging an insurrection against his own country; that he’s not above the law. We show that the United States stands for something. And those Republicans that do the right thing and join us will get attacked by the crazies in their party, who will run Trumpies against them in the next primary, thus making them easier to beat. The infighting in the party only benefits us.
Second: They don’t do that. (This is much more likely. I mean, come on, how can you have a trial when the jury is full of co-conspirators?) Trump remains popular, might run again, might start a new party that will siphon votes away from Republicans. (Or he gets arrested and can’t lead his sheep from jail). We get to hang this unpopular ex-President around the necks of those Republicans who placed politics above the country. The longer Trump is away, the less his popularity will carry him. Moderates and independents won’t look back fondly on the Trump years, and the support Trump had does not always flow to his sycophants.
So yeah, those Democrats who are saying his impeachment is ridiculous or a waste of time aren’t looking at the big picture here. Pelosi and Schumer know exactly what they’re doing.