Bitcoin will never become useless because of such stupid reason. If people need smaller divisions than 1 satoshi (10^-8 of BTC), the protocol will accommodate t

Bitcoin will never become useless because of such stupid reason. If people need smaller divisions than 1 satoshi (10^-8 of BTC), the protocol will accommodate that easily with small extension. But most probably, smaller transactions will be carried outside the blockchain on a decentralised clearing networks (where debts are cleared with real BTC transactions every day to limit the risks).