The mechanism underlying extension points (XPC, remote views), is pretty general, I would be surprised if the initial use cases were the end of it. ActiveX is

The mechanism underlying extension points (XPC, remote views), is pretty general, I would be surprised if the initial use cases were the end of it. ActiveX is pretty much a poster child for what happens when you rush this kind of feature, so, hopefully the assorted security vulnerabilities will not occur with Extensions.