A major PR coup for the government would be to keep HS2 plans and also announce a massive increase in investment in the classic network. I don't think most people are against HS2 in and of itself, they just see it as taking money and effort away from the existing railway. Which isn't true, but governments are in the business of fighting perceptions, not reality.
In the current 5-year control period (2019-24), the government has given Network Rail £50 billion to maintain and improve the current network (excluding major projects like Crossrail and the modest TP upgrade).
This is a huge figure and more than anything in the past.
In the last control period (2014-19), the government gave NR £11 billion for major upgrades including £6 billion for electrification.
Network Rail proved incapable of delivering the upgrades promised, and half of them have been descoped/cancelled to remain within the budget.
Part of that is the very difficult task of re-engineering a Victorian railway, both in cost and timescale terms.
HS2, like HS1, is new-build, and it is really much easier to create a new railway than upgrade the old.
Cancelling HS2 in favour of NPR is a way of delaying any significant benefits for a decade.
HS2 is essentially shovel-ready and has a detailed project plan and timescale for Phase 1.
By contrast NPR is currently a fantasy project with vague objectives ("faster journeys across the north") and no clarity whatsoever on what routes will be built/upgraded, or what services will apply during and after construction.
It is at least 5 years from work starting on the ground, and 10 years before any passenger benefits.
Plus probably a decade's worth of disruption to existing services to build the thing, similar to that suffered by WCML passengers during the recent upgrade.
