Yeah it probaby is the future but it does need to be of an equivalent quality to the HD broadcast the likes of Sky can provide to keep a lot of people. Using PLP as an example, as a hardcore fan who can't go without watching my team, I'll keep it because a slighty worse picture and some judder, while annoying, is better than not being able to see it at all. But many who don't care as much about a team may have been disappointed with the free trial and will stick with the free TV One live game and delayed games on Sommet and/or Sky. In fact even my brother who is a harcore United fan was disappointed enough with the trial on his setup in the weekend that he's probably going to stick with dodgy free streams and delayed MUTV.
It needs to be easy to use too. Sure it's easy enough for tech savvy people like some of us, but there are still a lot of people who simply can't cope with things like setting up apps or airplay, and setting up new routers that can cope with it etc. I even had to guide my Dad through the registration process over the phone, let alone setting up on his TV. The ideal I guess would be apps for every brand of Smart TV rather than exclusive deals with one brand.
Once everyone has fibre in a few years this way of delivery should start to become more mainstream. At the moment there are still too many people with internet connections that can't cope with HD streaming.