Ezio
Veteran
If they postpone ESC 2020 to the autumn (e.g. October 2020), they could start planning ESC 2021 in the meantime. Broadcasters wanting to take part in ESC 2021 (whether or not participating in 2020) would need to inform the EBU by mid October (which may be before the postponed ESC 2020). The EBU could pick a host country and in turn a venue for ESC 2021 could be chosen within that country, regardless of who ends up winning the postponed-to-October ESC 2020.
Or let the Eurovision favourites of 2020 already make contingent plans. They should make up their minds about venues now already and not plan to have super complicated stage. So, right after winning, they can kick of preparations for 2021 and not have a dragging host city bidding process.
I am talking about youooooh, Bulgaria, Russia, Germany, Italy, Lithuania, Switzerland and the luck you try to find it.
Besides that, have a Big 5 country ready as backup host (Spain or Italy, because they are hurting right now and deserve the gig the most)