I can't imagine this will impact the LHR T3 lounges (they are all mostly new). Maybe if T3 ever gets a substantial renovation
For BA lounges - I suspect the reference is more to yhe hodge podge of North American lounges where a oneworld lounge would make sense.
Equally would see some sense in converting the Qantas operated LAX lounges to oneworld branding.
And even the Qantas International Lounge at PER (given they no longer operate from that terminal)