I sure hope that you are wrong, but you do raise a legitimate point.
As I understand the situation, runDisney began in a large part to increase traffic to the parks (and all of the other ancillary revenue) during traditionally slow periods. I do not know how profitable the races are in direct terms, but I do know that there are really no longer many, if any, slow periods. If Disney can make a nice profit selling virtual races, and does need need the extra attendance, then it is conceivable that they could decide to transition to virtual only. The current pandemic has given many companies cover to make changes that would have been much more difficult pre-covid.
Having said all that, I still hope your sneaky feeling is misplaced.