Idk, I literally have no clue what could trigger something. Trump could have one last hissy fit, he could fire the whole executive branch. Who would put it past him not to?
Budget cuts to wrangle in stimulus spending could possibly happen, depends on the fiscal policy of Congress in the future.
Who knows, but arguing it could never happen is ridiculous when it's in the CBA for a reason, we have probationary periods for a reason, and litigation is next to pointless since it's civil in nature.
Honestly, a Republican controlled congress would be willing and capable of doing it. A pissy Trump would too.