I had a reply from BA this morning:
In light of the ongoing COVID-19 pandemic, our Management team made the difficult decision to temporarily close the British Airways lounge at Newcastle International Airport. However, they're regularly reviewing our entire operation given the everchanging circumstances. We've looked into your query in relation to the permanent closure of the lounge and although we have no confirmed date for when this is set to reopen, we also have no closure date.
Doesn't really add much more to what others have said.