This would be true if they were doing HS2 as London - Liverpool, or even God forbid London - Manchester, but they aren't - they are doing London - Birmingham as the first leg, a route which already has two well-established lines (Virgin running between Euston and New St, and Chiltern running Marylebone - Moor St). It is hard to see how HS2 will be a financial success on that leg at least, given that the Virgin service will only be about 30 minutes slower, the Chiltern one is the best service in the country, and both will be far cheaper for passengers.
HS2 would only have made sense if it went London - Edinburgh direct (or maybe with one stop halfway, York maybe), which would have been competitive with airlines and would make a lot more use of the technology. As it is currently planned, its hard to see how it will work unless this is some especially devious way of bringing in the inter-city provisions of the infamous "Option A" in the
Serpell Report (by spending huge sums on HS2 and then getting rid of "old" lines who duplicate the routes / cost HS2 revenue etc etc), whose route-map does look not dissimilar to the completed HS2 route.