The ideal measure should be neither revenue nor miles, but profitability.

However, I doubt that any airline has a reasonable way to track an individual's profitability to them.

So instead, airline management uses a proxy for profitability. And the popular recent view seems to be that revenue is a better proxy than mileage or segments flown. Who's right, British airways (always first with any reduction in benefits) or Gleff?

I think no one has a clue. What's going to happen is exactly what has happened so many times before: a group of airline managers is going to place a bet without any significant quantitative evidence to back it up. Pretty scary!