Pneumatic, but the question is, will technology surpass the tool before it becomes worn out. I have an OLD 60's? Snap on 1/2" impact, works fine, a little slow though; as well as a modern MG325. They probably have about the same power.
In future years I think we will see more advancements in battery powered tools in efforts to replace corded and pneumatic. But IMHO pneumatic will always be around, it is just to efficient of a platform to dump, all things considered.