You can see this sort of thing starting to creep into NFL coverage, I think mostly FOX Sports. They have a number of robotic cameras strung across the field on wires, and they use them to put together some fairly impressive replay scenes, though they can't follow the ball very well with them so you don't see them cut to during live action that often. I'm not sure how you start introducing this to sports like baseball with its non-uniform stadiums and fields, although things like the NBA and NHL seem like great candidates and I am sure you will continue to see this spread. I think ESPN's Axis uses something like it in baseball and basketball already, but that may just be fancy editing/extrapolation with existing angles.
You used to be able to choose among a group of 4 or more camera angles on a couple of the DirecTV sports packages as well, and you likely still can do that. I know NASCAR is deep into that sort of thing, but I am not a fan so I don't know much about it.