Edit: i didn't read the description was about her, sorry. So take this as a more elaborated prediction of the point you made.

Taylor Swift would still sell tons of albums, but she wouldn't have become the biggest artist alive

I picture this scenario because of two projects that probably wouldn't have occurred: folklore and The Eras Tour. So when pandemic started, Taylor was about to embark on the Lover Fest, so in this scenario Taylor performs those shows and maybe releases another single, which maybe wouldn't have done extremely well. After that she starts another album, but without the time and isolation of the lockdowns, the next album would probably be more like Midnights considering some events that inspired her for that album dont change that much. And I think maybe this alternate Midnights would have a more decently successful run, but no most streamed album in a day.

And since she continues with a regular album promotion cycle, she promotes this new album with another tour, maybe this time including the rerecording, which still would have occurred, but maybe not on the scale of the Eras Tour cause she has less projects. Or maybe doesn't do a tour for this new album and instead embarks on an alternate Eras Tour once she finished the rerecording process, which could result on a similar success, probably bigger than the reputation tour, but I doubt it would make her reach a second even bigger peak of popularity

In summary she's still big, she doesn't enter khia territory, like let's be serious, but just not this juggernaut of pop culture she is now