Realistically the 2019/20 season will not recommence, in all likelihood mass gatherings at sports events, etc will not be possible prior to July or June at the earliest.
By this time players contracts will have expired, fitness levels will have diminished, and momentum lost. The only, reasonable, solution is for those in a promotion position to be promoted and those in a relegation position relegated. With the team in the highest playoff place promoted also.
Obviously, those with their own vested interests won't accept such a policy, however if there is to be a 2020/21 season then there is no alternative; other than voiding the whole season - which hardly seems fair!