Brown makes his move this weekend, with a cabinet level putsch. Fear of this might keep Blair from going to the Middle East.
The Full Frontal Attack
Blair threatens or actually sacks Brownites for disloyalty. High risk of total civil war, Labour party self destructs. Blair’s heir wins a landslide for the Tories.
At some point early next year Blair steps down as Labour leader and remains as PM. Brown gets to campaign against Cameron for his own mandate from the party and voters. Blair tries to push his policy agenda as PM until the bitter end.
The Rat Fuck
Blair gets away without making any public commitment to a timetable, gets through Labour’s conference, screws Brown again and promotes a viable alternative candidate to Brown.
The Total Brown Victory
Blair commits to a public timetable. The exit date is soon, the spring at the latest. Brown crushes all internal opposition with a combination of fear and patronage.
Any more scenarios?