OK I'm going to lay out scenarios about what happens next. I'm not an expert so this is all open to criticism.
"Snuff it out" scenario
We quarantine, the cases go to zero and it’s just gone, maybe the summer helps. Unfortunately this tends not to happen.
”Turn it off and on again”
We quarantine, it goes down, we open up, it goes up again. This repeats until we reach herd immunity (60 to 70% of people have had the virus). This could last until the end of 2021 by some models.
The “scientific miracle” scenario
A vaccine is created and can be manufactured in enough quantities to give nearly everyone immunity, we jump to herd immunity immediately and go back to normal.
a) The virus is either gone permanently
b) The virus may need a new vaccine if it mutates next year
The small-pox-cow-pox scenario
The virus mutates into a
less deadly version that also grants immunity, we then get the weaker version and the deadly one is pushed out of circulation. Herd immunity, back to normal.
The Spanish flu scenario
The virus mutates to a
more deadly version and we just call this whole
going outside thing off.