This scenario also results in a Democrat taking the Presidency because in this event the President becomes the President Pro Tempore of the Senate. Which is currently a Republican, but if elections somehow didn’t happen that Senator’s term ends. Most of the open seats are then in states with Democratic Governors who would appoint Senators to replace the expiring ones. That would give enough Democrats in the Senate that they become the majority, thus the President Pro Tempore becomes a Democrat and then becomes President.
I’m an election worker and in my precint there’s an old folk home. Normally they swing by 6 or 7 different times with vans of different old folks from the home. Over the past 3 elections (March, June, July) in my county, they only brought one van and that was only because one person never requested absentee. The old folks home requested absentee for everyone else. So old folks are voting by mail at least in my area. And a smart old folks home will handle requesting all the ballots and ensuring they’re returned.