Pelosi lies IMO. The Dems know how to enforce party discipline and if any Dems vote against impeachment, it will be because Pelosi has given them permission so they can avoid the wrath of their district voters.
Democrats will fall into line for the same reason that the Confederate soldiers made Pickett’s Charge in the Civil War despite the fact that almost every one of them knew it would be a massacre. It would take more courage to tell Speaker Pelosi that this was a huge mistake than to go along with the herd and face the consequences in November.
Republicans taking back the House in November is not a sure thing this far out and the Dems may be banking on the short attention span of moderate voters. Its a bet they may be willing to make especially if they can run ads showing that Trump is an impeached president.
Republicans must go on full offense against these purple districts and make sure that they support attractive freshmen candidates in purple districts where Republicans are retiring or we may be looking a House driven impeachments for the foreseeable future.