It goes into law if the legislation gets passed. So it'd be very likely at that stage that it would be built. In my personal opinion the benefits of phase one alone are worth it. I think many members of the general public don't realise that HS2 will directly link in with the classic railway in the North Midlands. It's not a standalone thing wjere they're stuck on an adjacent line which becomes a dead end at Birmingham City Centre.Because the only reason the TOCs have for TV advertising is to try to increase revenue, and the only additional passengers they can attract are leisure / occaisonal travellers. The commuters are already travelling.
Anything is theoretically possible. Unpopular schemes and changes have been and will continue to be implemented.
It's not certain after it's passed either.
Honestly I don't think it'd be possible to just rip up the minimum service spec. and tell a line of towns for example, you are to lose one of your three morning hourly services. For a start you may end up with serious political opposition, due process would have to be followed, and after implementation you could end up with serious crowd control problems. As well as artificially surpressing demand by not offering the adequate number of services to cater for the numbers. If that were to be applied across a whole route then it could be an election killer, if it even got near to being reality.
)