1 sat is minimum. Next target can be a 0.00000001 ETH and then is definitely dead.
I don't think Binance will delist them as long as they have $3+ million volume.
Not sure if Binance rely on the total volume of the token across all exchanges on CMC to delist a particular token but one thing for sure is with each drop in price, the liquidity of the token also keeps dropping as more and more people lose interest. That eventually affects the daily trading volume.
We can already see that certain trading pairs have been removed. The trading pair with the biggest daily trade volume on binance was NPXS/BTC