A Chancellor dedicated to stamping out tax avoidance might well be a bit embarrassed at having created such a loophole, and would understandably be on the lookout for a way to block it without appearing to have to do a U-turn.
An Isa regime for pensions would do the job. So, of course, would abolishing the right to take a quarter of the pension pot as a tax-free lump sum — though that might spark a serious political backlash.
In fact, the risks of backlash and complexity suggest that the sudden overnight abolition of pension tax relief is unlikely because it would cause chaos and add hugely to costs.
Therefore, the smart money is on Osborne unveiling some kind of hybrid — enough of a move towards the Isa system to close the loophole and allow him to slash the amount he pays out in relief on contributions, but not getting rid of tax relief altogether — not yet anyway.