I almost suspect that Camerons recent statement is a play at statesmanship.
Bingo! The fact is that no-one knows what the economy is going to be like next month, never mind in 3 years' time. The likely scenario, confirmed by lots of rumblings round the ECB, is that the Euro saga will be coming to the end of the tunnel over the next year or so. Add to that the fact that inflation is likely to be very low and private debt much, much lower and you begin to realise that the doom and gloom is over-stated.
My predicition is the promised increase in spending + a very moderate amount to cover things like MPA. I don't see the NHS getting increases in 2016, like it has at the moment, which leaves a little bit of room for maneuvre for the likes of Education, transport, defence etc. The government have already made it clear that the extra cuts are coming from welfare.
Of course if Labour get elected then we all need to start looking for jobs!