More later ... but ... I agree that there is a very good chance there'll be some sort of chaos in the rankings.
So, imo, either:
1) The approach / formulas will be tweaked a good deal YoY in order to 'curve fit' the prior rankings into 2021's data set so that schools will all be "sorta in the right spot with no big surprises". Just imagine what would happen if (say) NYU, Dartmouth and McCombs were all in the top 5 using prior year's formulas for determining rankings? I doubt they'd publish a list with this amount of variance from prior lists ... unless they had VERY good reasons (see below).
... or ...
2) We'll see some schools move all over the place (think, UCLA or Cornell jumping from the mid-teens to Top 10 ... or ... a school like Columbia or MIT dropping down to the mid-teens).
The career services data will tell us quite a bit about how customer-service oriented the school is ... how much they'll hustle to really (!!) EARN the quarter-million dollars they're clients are paying them for their MBA degree.
Also, steps like what Kellogg did with their HUGE customer service gestures for applicants should (IMO) create some long-lasting good-will for many future years' of applicants. If I were looking at attending a FT program (or advising someone else on attending a FT program), the more customer-service oriented schools ... and schools with career services staff that really (!!) hustled ... would go way up on my personal rankings --- because, you just never know what'll hit during the 21 months you're getting your MBA, and you want to know that the school and administration will HAVE YOUR BACK during any future chaos.