If, hypothetically, you could run full-field events at multiple places at the same time, I'd bet you could sell out multiple NASCAR venues. Daytona, Bristol, Richmond, Indy, spring to mind. If you get a ticket to any of those places - you go. Period.
It's a moot argument because one of the cool things about NASCAR is that the whole league is on the field at the same time.
Yes, it is a moot argument because it will never happen. Given that fact NASCAR will forever have to accept the "brides maid" role and wonder "what if?"