I'll turn this on its head -- cost of printing aside, if Wizards needs three 300-page sourcebooks to explain how to play D&D5, I might not be interested anymore.
Me too. I'm sure the five-pound 500-page Pathfinder rulebook has triggered seizures in those trying to read the whole thing.
I'm cool with a $50 PHB, but if this is going to be the 'rules light' version of D&D, for that price it better contain a LOT of player options (classes, subclasses, feats, and spells). And resemble a very handsome coffee-table 'Grimoire' full of pretty art.