Common sense would say just let it go (that is, cancel it).
But in one hand, big time political and business interests are in play, both by the IOC, the JP government, the big TV networks, and so on.
On the other hand, it might be devastating for the athletes, some of whom might not be able to participate in the next Olympics (2024) or they will not be in a form needed for a medal or top-6 finish. The large scale boycotts of 1980 and 1984 have a lot of these personal stories.
Of course it is different to miss the OG for a once-in-a-century pandemic and a political decision.
My money is either on an Olympics with no spectators, or a cancellation in the last possible minute (say late March or so), after every alternative approach is exhausted or discarded as not viable (IOC and local organizers will deny the cancellation as long as possible, the same way they denied the postponement last year)