To add to this debate I would point out that this situation is not unique to long haul aircraft and I can cite several similar butt-clenching cases on short haul, where we plan our fuel to the nearest 100kgs with pretty recent info on delays. Any combination of late climbs, sub-optimal levels, unforecast headwinds, early descents and speed restrictions can see your contingency fuel burned before you make the holding fix. Add to that 'no delay' becoming an EAT out of the blue and suddenly your faced with calculating just how long you can stay in the hold and still have fuel to make an approach, divert and keep a bit spare for mum. When that time is reached its a choice of stay where you are, burn the div fuel and hopefully land at destination with a bit to spare or divert, burn the div fuel and hopefully land at diversion with a bit to spare. Very much between a rock and a hard place and diverting from a dual runway airport to a single runway airport seriously narrows down your options!