I don't think so, I think I'm accounting for the recent shift in realpolitik. Why would future Democrats impeach their own POTUS for using the DOJ and FBI to arrest their political enemies?

The Democratic party as you knew it is dead; it died in 2024, just as the Republican party as your knew it died in 2020. The Republican party has been reformed into the MAGA party, which bears no resemblance to the neocon Republicans of the 2000s. Just the same, the Democratic party will reform but they will not resemble the party of Clinton/Obama/Biden/Pelosi/Schumer. They are done as a political force.

Moreover, why wouldn't a future POTUS start off by arresting the current conservative SCOTUS judges? Decide on the arrest, make up a pretext, if US attorneys don't comply just fire them until you find one that does, like what they're doing to Comey right now. Make some vacancies and then appoint his own court. Or, just ignore them entirely, there are no consequences for not following their orders.