Bitcoin is already being used as an alternative to fiat when making payments for goods or services, and although it is not widespread at this point, it is pretty popular in some countries.
If Bitcoin gets worldwide adoption, it would not function much differently from how it's working now, it would only be operating on a wider scale.
Therefore, allowing many people to have bitcoin wallets is the only requirement for ensuring smooth transactions from the consumers side. They can be implemented in many payment methods, such as mobile payments and wireless payments.
There is no limitation on creating Bitcoin wallets and it's not technically the only requirement for ensuring smooth transaction; a Gateway such as a payment processor or lightening network is necessary to keep transaction fees low, reduce the wait time for confirmation and in the case of processors, convert the Bitcoin to fiat (if the merchant does not want to hold BTC).