Bath and Wells
Manchester (probably decided but not announced - see comments)
with Blackburn recently decided, and 7 other Bishops aged 65 or over, who will have to retire in the next 4-5 years. There may well be others who decide to retire at 65 (a further 6 are aged 61-64).
The full list of bishops, along with the CNC schedule for appointments, is here.
Justin Welby, as Archbishop of Canterbury, has a massive strategic opportunity here. The CofE has committed itself to 3 'Quinquennium Goals' (makes the pulse quicken, doesn't it?), the first of which is 'to take forward the numerical and spiritual growth of the Church of England.' That gives the Archbishop, as chair of the CNC, a pretty solid starting point for making the appointments above (plus any I've missed). If this is our top priority, then the top line of any person spec for these appointments is someone who can lead a diocese into numerical and spiritual growth.
It was pretty clear at the church growth strategies conference the other week that a massive amount depends on the leadership of the Diocesan bishops. Without that leadership, it's very hard to get the resources and energy of the church behind any agreed strategy. With that leadership, a diocese can change direction in significant ways, and see decline reversed and turned into growth. Justin Welby may have only the power of persuasion as 'first among equals', but with the chance to shape the leadership of 1/3 of CofE dioceses in the next 5 years, there is a great opportunity here to bring quality leaders into place.