It sounds like a silly question but, given the stubborn refusal of the polls to tilt towards the SNP's goal of independence, it might be even more important than trying to fathom the consequences of Yes.
An attempt to answer it was made by the Devo Plus Group this week. Devo plus is not to be confused with devo max. The notion of devo max may have entered the Scottish political lexicon but it is really little more than that. Broadly it means Scotland would remain in the UK and become responsible for almost all tax and spending north of the Border. The Scottish Government would pay an annual sum for shared UK functions such as defence and foreign policy.
The idea has been outlined – sketchily – in a number of Scottish Government documents, most recently Your Scotland, Your Voice in 2009, which was supposed to prepare the ground for a referendum in November 2010. But despite received wisdom suggesting it would be a popular option, no-one is so committed to devo max they have studied the practicalities and produced a fully fleshed-out system. That's despite entreaties from the First Minister who was keen to include it in the referendum.
Devo plus is different. Under the system a specific and considerable package of financial powers would be transferred to Holyrood. The Scottish Government would become responsible for all taxes apart from VAT and National Insurance but including a geographic share of oil revenues. At the same time it would take on responsibility for welfare spending, though not pensions. That would make Holyrood responsible for raising about two-thirds of its revenue, compared with less than one-quarter even under the new Scotland Act, which will give MSPs control over a portion of income tax from 2016.
The system has been set out in minute detail by the Devo Plus Group, an offshoot of the centre-right Reform Scotland think tank. Up until this week, it existed mainly as a bewildering selection of graphs, tables and statistics – which is perhaps why it hardly set the heather alight.
Now it's been given a constitutional makeover and presented as devolution's "final destination," a clear alternative to independence. Symbolically, devo plus would end Westminster's right to abolish the Scottish Parliament. The pro-UK parties, under the pressure from the SNP to set out their stalls ahead of the referendum, were duly invited to jump on board.
Will they do it? Devo plus – which would provide similar arrangements for Wales and Northern Ireland – appeals naturally to the LibDems with their enthusiasm for a federal UK. For Labour and the Tories it's a harder sell. Within Labour there is a genuine cross-section of opinion on the constitution. Some believe further devolution is unnecessary and see it in terms of "concessions" that play into the SNP's hands. Others believe greater autonomy would be good for Scotland. Politically they also see the added advantage of making it harder for a Nationalist government to blame Westminster for spending cuts. Scottish Labour leader Johann Lamont is regarded as being closer to the sceptical end of the scale.
The Tories look even less likely to back devo plus. David Cameron said he would consider more powers if Scots rejected independence but Ruth Davidson is known to be hostile to the idea. Recently they proposed a UK-wide constitutional convention which would be up and running before the 2014 referendum but whose findings would not be known by then.
Devo plus faces an uphill struggle. I suspect its fate depends on those stubborn polls. Only if public opinion shifts markedly towards independence will Labour and the Tories feel the need to throw their weight behind such a radical proposal before the referendum.