The problem is the 458s being released for refurbishment is contingent on enough 701s being in service to release all the 707s, and then the 458s.
The DfT are pushing the 701s come hell or high water, so I very much can't see that plan changing.
I agree if anything gets cut due to service reductions it will be the 458 plan. They're not in a good state, and I feel SWR might be rather underestimating the work needed to get them into a good condition. Whether they realise that before the work or...in the 442 fashion