Brainstorming some possibilities, not taking myself too seriously:
--2020 will be remembered as a year of death and disruption; the economy will suffer massively, perhaps enough to count as a recession.
--Many old people will die (something like 10%?) this is a big higher than the current fatality rates but I predict they will rise once hospital systems are overwhelmed. This will have a few knock-on effects: 1. Health care expenditures will drop for the next few years, since old and sick people are the biggest source of such expenditures and the population of old and sick people will be substantially smaller. 2. There will be a noticeable increase in average spending money available to younger people due to inheritances. 3. Politics in the USA at least will shift noticeably (though not dramatically) to the left, since the dead people will be disproportionately right-leaning. 4. Politics worldwide will generally shift in a more radical direction, since the proportion of young people to old people will increase. 5. One of the contenders for the US presidency might die before the election. (This is unlikely even if 50% of the world gets infected, but it is likely enough to deserve mention I think.)
--China’s dramatic and draconian measures to contain the virus will come to be seen as a success story, something that would have worked if only other nations had behaved similarly (and perhaps, if China keeps its border closed, it actually will work for China at least?). This leads to an increase in authoritarianism in general around the world, made substantially stronger by the general tendency of authoritarianism to rise during crises.
--The world will, in general, take pandemic risks much more seriously from now on, making it substantially harder for something like this (or worse) to happen again.