First of all, I don't really think the country's in all that bad of shape. I think we're led to believe that by a bunch of people who want to sell us something, or win our votes. But overall, I think it's pretty good. Prior to the pandemic, which was largely unavoidable, there was extremely low unemployment, homelessness was very low, very few people starve to death, very few people die of preventable diseases. On both a global and historical comparison we're not doing all that badly. Not quite as well as Norway or Japan, but pretty well.
But what I really wanted to say is, while this may largely be true (parties only caring about keeping or increasing power), it doesn't mean Republicans couldn't have voted for impeachment. There are two components of this. First, it wouldn't be all that shocking if the Republican establishment had, in the wake of the Capital storming, decided that Trump was not a good look for them and they were going to distance themselves from him. He'd already clearly lost all of his appeals on the election at that point, so embracing Trump doesn't buy them anything in the short term. They have to make a decision on whether accepting or rejecting Trump going forward is going to reflect more favorably in future elections. I'm honestly not sure what the answer to that question is in the mid-term. I think truly long-term, rejecting Trump now likely makes the Republican party stronger in 20 years. History is going to look back on the Trump presidency very unfavorably. In the mid-term there are still a lot of Republican voters who absolutely adore him, and I can see why you might fear alienating those voters. So anyway - yeah, not obvious to me what the Republican establishment would/should choose.
Second, each congressperson is an individual and not only a member of his party. Ultimately, she (or he) needs to vote in the way that she feels will preserve her individual power moving forward. For people from tightly contested districts or districts with large numbers of independents, I'd think this would mean voting for impeachment regardless of the party line. For red congresspersons from blue districts - of which a few exist - they'd almost certainly have to vote for impeachment. Those guys are usually elected because of a perceived combination of likeability and personal ethics. You don't see Larry Hogan embracing Trump. His future in Maryland politics would be dead in a heartbeat.