Maybe if they unlocked the cap on MGP that can be purchased with Gil, or maybe bumped it up considerably.
I can't say the devs are gonna care about uber rich players "Pushing" new players out of the market given that's hardly the primary focus of the game as it is. Although, I'm mildly amused by the idea of digging my heels in and keeping an item priced where it is and let whatever uber rich player I've aggro'd into aggressively dropping their prices continue to sell at a loss trying to "push me out" while I'm off doing something else in-game. Slowly, perhaps, but wouldn't they eventually run out of gil depending on how "aggressive" they sell at a loss?