Here is a possible plan scenario to add to the plan in the image. Clearly the Democrats "get it" that the easiest way to get "your" candidate in the US Senate is to have a vacancy and to be the appointer.
If Trump has the goods on Gillibrand, it would make no sense to bring that forward now. If she were taken out, her replacement would be filled by Andrew Cuomo. However - if Trump has the goods on Cuomo and Mark Molinaro is going to win the Governor's race (unlikely in the normal world, but not in Q's) - then after Marcus takes office - that is when you take Gillibrand out.