So bitcoins are not really good for everyday transactions. For example, you will never be able to use bitcoins to go shopping, unless you and the shop assistant are willing to wait an hour for the transaction to clear.

What will likely happen is somebody will develop an escrow-like service that will become widely adopted. The customer and merchant can have a wallet with the service and transfer funds between them instantly. This is how mybitcoin.com works. Transfers between two mybitcoin.com accounts are instantaneous.