I think that Nancy Pelosi wants the enquiry to stop or is sure of getting enough votes to start one. She must have been forced into it - fearing what is going to come out of the IG and other reports on what the Democrats have done in 2016 that would damage the DP beyond repair.
She also have a problem - she knows full well that Schiff is destroying any Impeachment enquiry and even if the Democrats manage to get the vote on proceeding with the enquiry on a patently illegal basis - the Senate will refuse to set up a hearing on the issue.
A public impeachment enquiry will be fun to watch - the Republican Party would want evidence from the Bidens, Pelosi's son, Schiff and the so-called whistleblower in public. That is going to be fun as well. If the IG report indicates that Obama was involved in the 2016 situation - he will also be called up to give evidence. Maybe the Democrats will sabotage their own motion - just to stop the exposure of their own behavior and corruption under the Obama administration.
The RP is likely also to call up witnesses from Ukraine as well - and that is not going to benefit the DP.
Anyway lets wait and see what happens on Thursday.