A lot. For a starter, it would mean a lot of the troops currently in the Armed Forces would have to leave (maybe not: It depends on whether that's a condition of severance), meaning that the UK would have to reduce it's military contribution world wide.
I'm personally against Scotland being an independent nation: We have only one heavy industry left (oil) and the North Sea oil stocks aren't indefinite. At best, North Sea Crude has about 50 years (and that's me being very optimistic) to go. The SNP has claimed that there are stocks in Scottish territorial waters, but whereabouts exactly is vague and looks more like either being in international waters or Irish waters. Even if these stocks exist, it would mean relocating a lot of the oil industry in Scotland to either the West coast or the North West Highlands at best - not areas that lend themselves to importing crude very well. This, although it would provide jobs in an area where even humanity is scarce, would also mean in lots of people in both Aberdeen and Falkirk losing out on jobs, especially with the knock-on effect.
Sadly, there are no other heavy industries left: there is one shipyard that employs less than 100 people and it seems to be the only one left, the coal mines are closed and so are the steel plants. While this many not seem to be immediately a problem, it is: These were places that employed people in their thousands, if there's no-one like that then jobs and the economy of an independent Scotland will soon start to dry up. There are also less foreign investors than there were 30 years ago and the only people who want to invest seem to be coming from China. Would you want companies that owned by a totalitarian regime to own part of your country?
However, there are those that claim this is nothing: There is an extremist part of the nationalist cause that is all too vocal who see the idea of an independent Scotland where we all live on bread an water as the price for being 'free' of Westminster rule. The problem here is that they don't see that nobody wants to starve for the sake of their fantasies. Some claim that there will be some lean years but then everything will be rosy again, but where's the money coming from?
But, and this has to be said, there's a lot at fault within the Union. Britain's state of the Union is woeful and all too often (especially under the Conservatives) Scotland suffered badly. For example: When the Options for Change document to cut back the armed forces was brought in in the early '90s, many of the Scottish regiments were cut drastically or merged with other regiments. That may sound par for the course, but consider this: These regiments were so over-recruited at the time, they had to lend out whole companies to English regiments to make up the numbers. In other words, units that could turn recruits away were disbanded or merged, even though they had recruits to spare. Contrast this with the fact that there were English regiments who were left alone. Why? Because the places where the English regiments had recruited had returned Conservative MP's to Westminster, whereas the areas where the Scottish regiments had recruited had returned Labour, Lib-Dem and Nationalist MP's. Consider also the fate of Rosyth Dockyard: It was outfitted to service Nuclear submarines and was the largest employer in the Fife area. But the contract to refit Nuclear submarines went to a Navy yard in England instead, simply because that area had returned a Conservative MP and Rosyth a Labour one.
Also look at the coal and steel industry in Scotland: Under the conservatives these were effectively destroyed. There are no working coal mines in Scotland and our last steel plant was closed years ago - it's now redeveloped and all traces of its existence removed, so that any Independent Scotland would have no chance or restarting it without great expense.
So the problem is this: I believe that Scotland will eventually cede from the Union, but I don't think the time for it is now. In Scotland, we have to build up our industry again to the levels it was at in the 1930's and not live off the fantasies of people who think it will be a land of milk and honey. However, the Union can be saved if (and this is a huge 'if') the MP's at Westminster can get it into their thick skulls that Scotland is not its whipping boy and to get over theirpetty grievances that have cost this country so dearly.
