Then we'd all better get used to saying "President Clinton" without too much bile coming up.
The GOP hasn't even begun to lift a finger against Trump in that way... and we're down to 22 business days until the election. I don't think the GOP would even consider it until Tuesday (after Columbus day).
If they did, then, consider it... I'd hazard we'd see a decision by Thursday (13 October). Pence would then have to find a Vice-Presidential candidate that the GOP would accept. Best case for that would be the following Monday (17 November).
Then the states would have to print up new ballots. Maybe they'd be ready for mailing by Thursday or Friday of the same week (20-21 October). Hopefully, the post office would get the absentee ballots and process them on Saturday (22 October) and then get them out for delivery (3-5 business days - or sometime around the 26-28 October).
And that's if *EVERYTHING* works perfectly and with no delays. I didn't even go into how long it might take for the election officials to place address labels onto the ballots for mail.
The more likely scenario is that we'd get those ballots out and into the voter's hands within 2-3 days before election day.
And that risks a few million votes right there.