Thinking about this earlier - and there is technically no need to cancel Eurovision this year - just swallow hard, take a deep breath and downsize it for 2020.
I know this is a tough sell for some around here, but.
Put your presenters in a studio in Hilversum, a couple of hundred medically signed off audience members, and off you go.
No live performances just play out the winning songs from each of the participating nations in video form from either the official video - or the performance that won the national heat.
Jurys vote on Friday. Televote as usual on the 'live' final on Saturday evening.
Have the singer/band entry with the national jury marks announcer in their local studio (sorry, NDR your outdoor screening in Hamburg will probably be cancelled this year anyways) and there we go.
Yes, NOS's Eurovision would be turned into a Saturday peaktime pan European MTV circa 1992 pop video programme, but at least it gets the programme out and keeps the show on the road in difficult circumstances.
Seems like your idea is indeed the back up plan.
The director of RTVSLO (slovenia) says today
At the EBU, they are preparing as if Eurovision will be held as normal. I am personally in touch with management who has a plan B where we [the national broadcasters] will become more involved. In Slovenia, this is supposed to be in the TV studio.
If this scenario were to be fulfilled, each member would show their [own TV studio] recording of their performance. That’s what they’re thinking. They are still talking about everything, but in principle they are acting as if Eurovision will be held in Rotterdam [as originally planned].