Some are obvious: GPs were trained as doctors, not managers, and many won't want a management role forced upon them. There is a big problem over inherited PCT debt; and uncertainty over the minimum size of consortium needed to minimise financial risks. Individual and corporate skills risk being lost to the NHS as PCTs are wound down - especially if the better managers aren't assured of a job in a consortium.
Other problems are less obvious, but still very damaging.
For example, every practice has to be part of a consortium and any practice failing to join will be allocated to one.
But what about the reverse situation: the consortium which doesn't want to admit a particular practice (whether applying voluntarily or by allocation)? A consortium may have legitimate reasons for refusing, such as a mismatch with local government boundaries; historically separate referral patterns; or difficulties with patient transportation. Will it be able to say no?
Similarly, could a consortium expel poorly-performing practices which can't or won't improve? If not, how can it protect itself against their negative effects? If it is allowed to expel them, what happens to those practices? Will they be forcibly allocated to another (probably unwilling) consortium, in the same way as difficult patients are allocated to other practices?
Alternatively, will a practice expelled from a consortium also automatically lose its contract with the NHS Commissioning Board? If so, its GPs will lose their livelihoods and their practice investment - an effective and suitable threat if the practice is of poor quality. But what is to stop practices in a consortium ganging up to expel an individual practice purely for administrative convenience, envy, or because of personality clashes? If expulsion is to be permitted then complex checks and balances will be needed to ensure fairness, plus an appeals process - all cumbersome and expensive.
These scenarios aren't hypothetical: they are bound to occur. Huge problems lie ahead if the regulations aren't crafted very carefully. The devil will be in the detail.