Out of body experience
I think what we'll see is more akin to a death not because people won't use UC but because the dozens of apps with some from of UC included that don't talk to each other will become so frustrating that the UC features of most apps will be dropped. If you're running 4 different applications all of which have some UC connectivity with your co-workers which one do you use? Where do you go for conversation logs if you want to do some review? I think there will be a lot of noise for a little while until a clear winner is sifted out but then you have to hope their UC component doesn't get axed in an update or you just stick with one platform for communication and let the other apps do what they are best at.