Generally correct: definition of "major" mutations vary.. ones that confer selective advantage are what I would consider noteworthy. Europe last year, UK, SAfrica, Brazil/Manaus (which some suspect is descended from SAfrican strain), California... all of these are capable of mutating further and creating the next faster spreading, more deadly variant.

Some research suggests Covid-19 spike proteins still have the ability for 100+ fold increase in ACE2 binding affinity. Should those mutations arise, it would be catastrophic.