I don't think NR will be too worried, the key point about a ROC is it's not 'hard wired' to the infrastructure like a PSB. So a ROC can be relocated in future to anywhere that resilient coms are available, without too much difficulty or cost.
Consolidation of ROCs makes sense, because it reduces costs, and a larger staff team in one location will be better able to deal with contingencies than lots of smaller teams, who may become overloaded by an incident.
So in the fullness of time, it's entirely feasible that the whole UK network will be centrally controlled from just 3 or 4 ROCs, geographically dispersed for resilience. Like Air Traffic Control, or indeed the motorway network.
As you say the main issue is having the right skills available locally for staffing.
I don't think your consolidation argument necessarily follows.
There are two streams to this decision, Control functions and Signalling functions, and in many ways, having each of them separately together gets you the benefits, but do they both need to be in the same place? Do Controllers ever speak face to face to Signallers?
As far as Signallers go, once you've got enough signallers to warrant a Meal Break Relief Signaller, and a Signalling Shift Manager, does it really matter whether thats the limit or the same is replicated a few metres away? Theres only so many workstations any particular signaller can sign, so I would suggest that broadly the spread of PSBs, with their signalling control extended to the logical surrounding areas, would probably have been optimum. Its also worth considering how many people who are suitable and willing to work as signallers live within a suitable commuting distance of a particular ROC.
I'd suggest that there is no particular reason or need for Control functions to be in the same place as Signalling functions, and once a signalling centre gets up to around 7 workstations there no benefit of having more than that in the same location.