This does appear to happen. If OR thought the cabinet was commercially-viable at first, it would cause the area to be marked grey in the county plans.
If it turns out to be unviable after all, perhaps due to power problems, it seems that it doesn't change status within the county's BDUK plans. See, for example, this report from Craven council within the North Yorkshire BDUK rollout
, for a case of 3 cabinets that did this. There, the council obviously took steps to cope with the situation.
Another possibility is that various councils are now vying for an allocation from the second tranche of BDUK funds. This seems to be causing new OMR processes, which should catch cabinets like this, and get them re-included in the plans.