Some of the most enthusiastic nationalists would like to revert to an independent Scottish currency, which does not have a great historical track record. By the 18th century the value of the 'pound Scots' was so much less than that of the English pound that some Scottish merchants refused to accept it and English notes increasingly circulated north of the border. It's true that was long before oil was found in the North Sea, so maybe things would be different this time round. In theory the residents of Berwick and Eyemouth would be facing the prospect of having to carry two separate wallets around with them every day as they commute across the border to work and shop, but in practice we can safely say that shops close to the border would accept both currencies. And of course there's always plastic - though you really wouldn't want to have to pay your bank's foreign transaction fee every time you nip out for a sandwich. The glory days of Eyemouth and Berwick as centres of smuggling and cross border profiteering would then return. I imagine that organised crime is already renting the warehouses for when Scotland introduces taxation that differs from England on alcohol, cigarettes, or anything else.
Even without a separate currency, it is certain that we will see 'benefit tourism' if Scotland maintains more generous social welfare provision than England - some older people in the Borders are already moving a few miles north in order to qualify for free nursing home care. If Scotland funds this generous provision by raising income tax we will also see some working people moving south. This movement of payers out of and beneficiaries into an independent Scotland could put a great strain on the new state, and so long as it remains within the European Union it cannot do anything to stop this migration. And it's us here right on the border who will see the most population movement. Granny in Scotland, the weans in England, seems the likely future.