I don’t know. The virus lives much longer on just about anything else, so your credit/debit card touching a terminal, or your fingers putting in a pin, or even your phone touching a touch point may be more hazardous than cash. They haven’t really proven it one way or the other. The only thing proven is simply not being physically present when you pay, which isn’t always practical (just ask the people ordering grocery delivery who are now on waiting lists more than a week long). I don’t want to contaminate my cards or phone (especially the phone which is close to my face for talking). I don’t know for sure yet what my long term payment plans are. Sticking to my budget is easier with cash (don’t have, don’t spend), and I don’t have to worry about my cards being compromised. My sister, who uses her cards all the time, gets compromised a lot, even at her bank. But I do want to reduce my virus risk as low as I can, so everything is on the table to accomplish that.
As to the question at hand, I agree that buffets in their current format will go away. They could go back to a cafeteria format, where the food is behind glass and plated for you. A person could still visit the line and get more, so AYCE wouldn’t have to go away, but the contamination risk would be greatly reduced, even for things like norovirus.