He is pursuing acts to play both dates, not just one, and they seem to be way ahead of the curve in just about every aspect of the festival in comparison to years past.
I would like to know why you think it's unrealistic. Do you realize how many bands / acts there are, that could fill out the undercard next year, for GV to choose from?
Will there be variation? Yeah I am sure there will be a couple of acts that differ. But 20-25% of the undercard is a bit extreme. This is one of the premier music festivals in the US - if not the best overall - and you mean to tell me you think they will have problems finding acts that will commit to two weekends?
You say you want arguments as to why we think this can work without providing any real reason for your prediction other than, "I think this is wishful thinking".