Debt, demographics and geopolitics aside, swing factor is whether artificial intelligence can revolutionise productivity

The first quarter of the 21st century is almost up, assuming one regards 31 December 1999 to have been the last day of the last millennium (non-partying pedants insist the date actually fell on the final day of 2000). It is the cue for analysts at Deutsche Bank to remind investors how much can change in the course of 25 years, in this case from the days when Nokia phones and fax machines, rather than iPhones and Amazon, were everyday features of life.

Here’s one jaw-dropper: back in sunny days of 1999, there was a live debate as to when the US would pay down its entire stock of government debt. The Congressional Budget Office (CBO) reckoned the glorious day would arrive sometime in 2013. In reality, borrowing headed in the other direction almost immediately – and the US debt-to-GDP ratio is now above 100%. The CBO reckons annual deficits will take the ratio to 160% by 2050.