Much of what you suggest already exists in the US; protocols are standardized at the state level and the post-9/11 emphasis on disaster planning has gone a long way to ensure interoperability. The existence of waivers, special projects, and service protocols reflects the awareness that not all services are staffed with equally competent providers, nor do they all need the same scope of practice.
Yeah, most of those suggestions were fairly peripheral to the main idea, of centralising EMS and seeing it as a healthcare function.
When I'd worked in EMS, we often had bizarre variations between different regions in the equipment, drugs, and protocols used.
There are definite cost savings in reducing redundancies, for example, if you purchase ambulances for the entire state / province, the per unit cost goes down.
I'm also not sure that there is a real need for variations in protocols between different regions. I accept that providers with long-distance transports, or transporting to less equipped facilities are going to need to have access to therapies that might not be useful if they're transporting 5 mins to a major trauma center. I'm just not sure why one service with an hour long transport time needs to have different protocols from another service with hour long transport times.
If you centralise things, why not have one set of guidelines for transport time <20 mins, one set for more than 20 mins, and another set covering special situations for flight providers?
The best reason your other suggestions haven't been implemented is that they involve infeasibly large areas. The coverage areas you envision would contain vastly different communities with differing EMS needs. Combined dispatch for large areas with high call volumes is also potentially inefficient and stressful. I agree that smaller communities might benefit from combining their EMS agencies, rather than relying on mutual aid, but that solution can't be applied indiscriminately to all areas.
I agree these are large areas. I disagree as to whether it's feasible. If we consider areas that are large in population, well this system pretty much already exists with the NHS in the UK. If we look at areas that have a large geography, or remote regions, look at the geographic size of the Canadian provinces.
Why does a patient in community A need different treatment to community B? How different are the needs of two communities? Perhaps one area sees more highway trauma, and needs less continuing education in this area because they keep their skills up by constant use. Perhaps another region sees more drug abuse -- but I can't see how the medicine becomes fundamentally different.
I don't see why dispatch amalgamation is inefficient. It seems like it would be far more efficient. The dispatcher has to do the EMD cards. They can do that on a patient five blocks away or 500km away. If you have enhanced 911, you can get caller location. There's definitely issues with poorly-marked rural areas, and people who don't know their address or legal land description, or whatever. But I don't think these necessitate the existence of small regional centers. Take this model, and you can start doing better 911 service by throwing a nurse or physician on the end of the phone for callers with selected complaints to direct them to other resources than an ambulance.
I guess it all rests on where the cost-benefit lies.
A major advantage to centralising a system is that you can place resources where they're most needed, instead of in the communities that have the most tax dollars, or the most political impact. If you have a small town 300km from anywhere, maybe it does need a dedicated ALS truck, and a couple of BLS rigs, just because it's a million miles from anywhere. The system ends up being built to cover the call volume. You can move resources around more efficiently, because you don't have to worry as much about politically created borders.
Granted, perhaps you're right and I'm wrong? But I'm yet to be convinced that what I'm suggesting is impossible, impractical or undesirable.
. 
