If Scotland choose not to accept a proportion of the UK debt as a negotiation strategy, then this is not a massive blow to the UK. The debt is likely to increase over the next few years because of Scotland as they spend more than receipt in tax revenue consistently - even when the UK as a whole does the opposite. Without Scotland the gradual reduction of deficit should be faster.
Additionally - Scotland not accepting a proportion of the debt will allow the UK to reasonably cease backing of any major infrastructure projects in Scotland, committed investment etc with virtually zero negotiation. It will also immediately stop any negotiation on currency sharing, rights Scotland may think it has to Bank of England reserves etc.
It will also quite probably increase the cost of borrowing for a shiny new Scotland, which as they will now be a competitor to UK plc, can only help the UK as a whole when investing in infrastructure, talking to prospective investors, manufacturers etc.
Although the UK needs to continue to honour all debts, that £100+ Billion need not be lost forever. Given 65% of Scotland's trade is with the rest of the UK, I'm sure something could be found to increase tariffs, make operating costs in Scotland so expensive the business moves elsewhere and the taxation revenue also - in fact as already pointed out EU banking legislation and the need for some international businesses to be in the EU may make this happen anyway.
Essentially, if Scotland vote YES to independence then the UK Government ceases to have any duty of care for their citizens and should seek to protect the well being of UK citizens. A clean break with no further financial liability and removing any net of support for Scottish people, businesses, companies and the expense of risk to the UK would seem to be worth £100 Billion.
In the short term, any disruption to the Scottish economy will have an immediate impact on thousands of UK companies and probably reduce tax receipts. In the longer term, the chance of migrating the some of the Scottish economy to the UK and other EU nations without the cost associated with the most "expensive" old UK citizens - what is that worth?
If you have a vote this month - please, please, please vote YES.