Combining cash app and Bitcoin lightening network will definitely solve the issue of scalability in the transaction process and this will make payment to be on time and with minimal low fees, but still the success of this will depend on how many merchants and outlets will be willing to accept Bitcoin as payment.
Bitcoin will definitely become a global currency for everyday payments as we journey and this is one example our of many development that aid usage of Bitcoin for every day payment.
These merchants will always point to the volatility of Bitcoin as the reason why they would accept Bitcoin. As it becomes more stable in the future, more organisations would see the need to have an alternative to fiat. It's a good move from Square if their main aim is to use Bitcoin in a decentralized manner.