Is the Reading-Basingstoke electrification really 100% safe just because it's now part of the GWR electrification? Is it considered a "core" part of the GWR?
Well it was built as a GWR branch line, even though it seems to have found itself in NR's Wessex route today.
I think it's safe. It was added as a necessary part of the Electric Spine, but it does have a separate business case as a regional/commuter connector.
It's case is at least as good as any of the Thames Valley branches.
Dual voltage services via Basingstoke also become possible, as well as cascading more DMUs.