1. A lot of newly built houses, particularly those in a big development, will have access to cable, installed as the houses were built.
2. Yes, an attic aerial is often an alternative to rooftop.
3. New built houses just don't have aerials fitted anyway, that's an outside contractor's job, to be chosen by the new house owner.
4. Terrestrial TV as we know it has a limited future. In the not too distant future all analogue transmissions will cease, which means that big 'ol tower at Crystal Palace will be festooned with nothing but mobile phone repeaters and some dubious military aerials methinks.
5. Soon all TV signals will be digital which will mean either you'll need a digital equipped TV or a seperate box to receive digital signals, on sale now, both of them. And you'll need an aerial for the digital signal. However, in most areas the digital signal will be stronger than the old analogue signal so an attic or even a small indoor area will often suffice.
The days of masses of big ugly rooftop aerials are numbered but for the immediate future, they will not be going away.
Hope that helps