In his final appeal to the airport commission judges, Boris Johnson on Tuesday submitted a report claiming his Thames estuary plan would regenerate east London and create thousands of jobs. Hours later, the London mayor formally applied to be MP for a west London constituency, Uxbridge and South Ruislip, where many businesses depend on the nearby Heathrow airport he supposedly wishes to close.

As early as next week the commission may ease any Johnson embarrassment by finally dismissing the idea of a brand new hub: a move Sir Howard Davies was itching to make a year ago, before conjuring an elaborate political fudge that allowed what he called an "imaginative" proposal to stay in its own mini-race, off the actual shortlist. Further evidence gathered by the commission – including a damning environmental assessment – suggests any further reprieve will only be temporary. Johnson's plans have a certain logic, but not enough for another major politician – or airline – to support them. The chances of an estuary hub appear slim outside a future Boris-led government – a situation where reasons for concern would go some way beyond where to build a runway.

That leaves a bigger Heathrow or Gatwick in the mix – if indeed the airports commission holds sway. Despite years of the coalition effectively delegating the decision to Davies, politicians on both sides refuse to back his answer: effectively, they will endorse his recommendation if they already agree with it. His conclusion may be delayed until several months after the 2015 election, giving any new government time to make its feelings on the issue clear.

The political headache for any side would be a third Heathrow runway. The relatively uncontroversial – if relatively unnecessary – Gatwick second runway looks the only recommendation with a chance of securing quick approval when the report eventually lands.