If you assume the shopper still wants the product delivered, but is only going to re-select the store they are buying it from, not much of an impact on UPS.
If the assumption is that the shopper is going to visit the store to make the purchase, obviouly, UPS would be negatively affected.
I think some time has to elapse so that we can monitor any change in customers shopping habits.
The amount of time to observe will not be long, maybe 6-8 weeks. That would be conclusive enough( for me) to make a strategic investment decision, if warranted by the numbers.
My feeling is we would be well ahead of the herd with that 6-8 week experience.