I think there's a tendency to ask the SNP to come up with solutions for all questions about how to split up England and Scotland.
However, if we think about the time after the Yes vote, I don't expect all Scottish Unionists to commit collective harakiri.
What I do expect is that the vast majority of Unionist politicians will pick themselves up and start working to secure an independent Scotland the best possible deal.
To be concrete, I would expect all Scottish members of the UK government – Michael Moore, Danny Alexander, David Mundell etc. – to resign the next day. It's possible that all Scottish MPs would resign, too, but I find it more likely they'd stay in place in order to help keep a tab on the UK government's activities.
The next step will be the formation of an independence negotiation team. Of course the negotiations could in theory be handled by the SNP, but it would make better sense to make a united negotiation team with representatives from all the mainstream parties in Scotland, and consisting of not just MSPs but also MPs.
As part of the process of assembling the negotiation team, I expect a lively discussion on the way forward for Scotland. For instance, the other parties might challenge the SNP's plan to leave NATO. This is what makes the current situation so annoying. Labour, the Tories and the LibDems keep criticising the SNP's concrete post-independence policies, but they don't have to tell us what they'd do instead; they just tell us they want to preserve the Union (which is fair enough, of course), but they don't want to answer what it is they want to do if independence happens anyway.
Anyway, once the independence negotiation team has been formed and the negotiation mandate agreed on, things should proceed quickly. Certain questions need to be resolved before independence, but many other questions can probably be ironed out afterwards, so long as the interim position is clear.