They'll try stick it in newbuilds somehow (via legislation probably). How such a thing will work/go down with telcos and whether it is faster or not, remains to be seen. You don't get yottabits just yet.
It seems to me that current network infrastructure is incapable (all telecoms providers that is) of such speeds without siginificant investment. No-one wants to put large amounts of money into (dud) technology (Apple V Sumsung, Blue ray/HD-DVD, Video 2000/VHS/Betamax, 8 track/cassette etc for example) and make a huge loss on it, taking down said telcos with it.