Pairs would have to be significantly redesigned to accommodate the elements for two people who are closer in size - even if you had same-sex pairs with individuals who had a substantial size differential.
I've had some thoughts about this from a technical/elements point of view and would be interested to discuss. In a separate thread.
Some previous threads on the subject:
Tennis has mens/womens doubles. Synchronized swimming has female pairs. Why won't they allow same sex pairs/dance events in skating? I think it would make skating more exciting and give countries with a lot of depth (US, Russia, Japan, Canada) to allow more skaters to compete domestically...