While there are a number of services like roads that would be used by people from the surrounding communities if the development moved out there, there are also lots of services that Edmonton wouldn't be required to provide to these areas. Transit service, emergency services, utilities, etc. that are very costly to deliver - especially to these sprawling neighbourhoods. I have seen a lot of the information on the tax costs/benefits of these neighbourhoods if they are contained within the city limits (where they are a significant drain on financial resources relative to their tax base), but it would be really interesting to see an analysis of the cost of having these people sprawl into surrounding communities to Edmonton and whether that would be better or worse than allowing the development within the city limits.