Maybe. But if something widespread riots, or perhaps a failure of the power grids outside of major cities in a few swing states causes a sharp decline in in person voting on Election Day, the left will have far less to worry about, because their votes will have already been cast.
Yes, hence the blurb at the end that this is all dependent on GOTV game being as strong as 2016. But theyre in a big blind spot right now where theyre drinking their own Kool-aid and not firing up the ballot printing presses because theyre comfortable with the topline stats.