Disney said you could only reserve 3 and all in one park. Up until you actually used the first one you could change the 3 to another park. BUT, this does not peclude Disney from handing out additional FPs on the same day, and at other parks. By no means stated anywhere, but not forbidden.
I think the one park rule makes perfect sense. Most people, especially first timers would not understand the logistics and time involved getting from ride a in MK to ride B in AK. There would be a lot of frustrated and upset people if they allowed this. But, if they allow additional FP's in any park then you will have the opportunity to book at that time and if available.
A lot of the differing views on this depend upon certain assumptions. Some feel availability will be very limited an therefore reservations will need to be made 60 daysout and no ther FP's will be available.
I think FP's won't sell out, there will generally be plenty, people will not rerve 60 days out, there will be lots of swapping right up to and through day of, huge inefficiencies in the current system and many unused FPs will be recovered and reissued, many will not book or will book characters, fireworks, and parades in droves, and it will actually work out fine while we learn a new set of tricks to maximize its effectiveness.