Binance would de-list it for insufficient trading volume and/or lack of project developments/communications, etc
I guess what's more important for Binance is just the trading volume because it's where they make money and PundiX now is still having a trading volume of over $500K daily, and it's sufficient enough for Binance to make money on the token, maybe if the volume will drop below $100K, then we should consider that as a hint for a possible delisting.