Fattus would do a good job, no?
Can't see Flower going, can't see him being pushed out either. What i can see is a gritty old warrior of a cricketer who has formed a great team that for whatever reason (age, over confidence/lack of desire, mental issues, injury etc) is now entering that phase I hate; 'transition.' (Surely every bloody team ever is in transition?!?)
Does he have the will to build a new team? I believe so. There are also some good signs to point towards the future; Root, Carberry (maybe not long term future due to age, though he is a fine athlete, but he is new to the team) Stokes and it looks like Bell has finally developed some grit and nous to go with all that talent.
Cook
Carberry
Bell
Root
Stokes
Broad
Bresnan
Anderson
Is a decent 8 to form a core of a side, with questions marks over KP, Prior, Swann and Trott. If at least 2 of them remain for at least a few more years and get their heads back in the game, then we have some wonderful senior players to pass on experience as well as being talented cricketers.
Wh else gets a proper go now? Onions? Finn? Bairstow? Taylor? Morgan? Tredwell? Ballance?
All that being said, i do believe Flower will be there to oversee whatever happens in the coming years.