How's this for a rough go at organising into 10 franchises, tried to get best geographical coverage and balance of rivalries:
1 Yorks
2 Lancs
3 Warks/Worcs
4 Durham
5 Derbs/Notts
6 Glos/Glam
7 Hampshire/Som
8/9 Middlesex, Surrey, Essex, Kent, Sussex into 2 teams.
10 Leics/Northants
Teams would share out revenues to make sure the smaller counties still get funds from it, and in some cases (Glos/Glam being the obvious one) possibly split the matches between their grounds. Main cities would be Leeds, Manchester, London x2, Birmingham, Nottingham, Durham, Southampton, Bristol, Leicester.
Alternatively base it on cities and merge the counties to suit - Bristol, Cardiff, Manchester, London x2, Southampton, Nottingham, Birmingham, Durham, Leeds. That's one city for every major cricket area (also all the international grounds), plus an extra team for London. Makes more sense as a concept, harder to sell to the counties though.