What's the drop dead date, if you'll pardon the pun? The date someone new would have to be "annoited" by the Democrats in order to make ballots for early voting?
Ahh, it is already dicey.
The state cut-off dates are well before the early voting begins.
In addition, about 30 states have agreed to defer to the DNC process and approval for replacing a nomine but that leaves 20 or so that have a review process and various hoops to jump through back in the states- which chews up time.
Ohio already had to pass a bill to meet the current convention date lateness. Every day you get past, say, the middle or third week of August, you pick up a new problem.
In Ohio, there was sort of a bipartisan feeling (even if through gritted teeth) that you needed to move the deadline and could not just disenfranchise all the dem voters. Democracy required some flexibility there, arguably. But I don't think one can assume that republicans will not fight- tooth and nail- any last minute shortcuts to let dems on ballots just because they created a mess. Gonna be a lotttt of rich lawyers before this is over.