84 year old being weaned off a non invasive ventilator with suspected copd. what will happen next if lungs don't cope?

COPD: Hopefully you can maintain oxygen saturation with small amount of supplemental Oxygen with close observation.

CPAP/BiPAP: Some patients benefit from nocturnal support with CPAP or BiPAP chronically.The patient should be evaluated for sleep apnea and arterial blood gasses should be analyzed. A persistently high pCO2 or acidosis may impair weaning. Look for complications like infection, concomitant congestive heart failure which may be contributing