australia seems to be doing ok since gaining independence from UK.
most of other countries too. no reasons to suggest scotland would be different.
what's interesting is that whenever someone tries to get independence the whole world around them tries to make it harder for them and scare them with things like "oh but you'll have to reapply to EU" or do this or do that, instead of saying we recognise your decision and will work with you to make transition as painless as possible.
Yey, Georgia and Ukraine spring to mind.