Indeed it is difficult. However I think "alongside" means side-by-side, at the same time, so
– Phase 1 OOC - Birmingham Curzon Street to be delivered "early 2030s" (no change)
– What's happening with the Handsacre link to the WCML is unclear (though I would think it's still part of Phase 1, despite the change in wording in the progress update)
– Phase 2a Brum to Crewe is being "replanned" and will certainly be delayed beyond 2033
– Phase 2b/Manchester, HS2 East/the Midlands leg, and Euston to be delivered after 2040, the last one as previously rumoured.
Really it means this government is committing to OOC-Curzon Street, and the next government will decide whether to proceed, if at all, with the rest of it.
Public investment delivers economic growth which pays for the public investment through higher tax returns. For whatever reason, governments since 2010 have turned away from this, while at the same time making private investment harder.