SARS-COV was never very wide spread in the population and was contained before it became an epidemic. I doubt it mutated, as coronaviruses are pretty stable. The 4 corona viruses that cause common cold sysmptoms, (HCoV)-NL63, -OC43, -229E, and -HKU1 are all very much the same as the ones that infected people 30 years ago. MERS is still the same Camel virus that just happens to infect humans too. No one knows exactly where SARS1 came from, but it is almost certainly an animal virus like MERS, and just exists in some animal that people have little interaction with. SARS-COV2 is too widespread to put back in the bottle, and being a coronavirus, might not mutate enough to make a difference for a very long time.
I guess we just got lucky with SARS1 and MERS.
I remember the SARS1 panic of 2002-3 in some cities and that the front-line medical staff were dying. Many patients were on ventilators and their lung xrays were awful. There was a run on Tamiflu because it seemed like the only medication that was working. And then...nothing. It died out. Never returned. I really wonder why.