Would an end stage copd patient be able to come off ventilator?

Possible: It is possible but very difficult. There are many factors influencing outcome. Mental status, nutrition, extend of lung disease, cause of lung disease, coexisting infections or heart diseases.

Unlikely: If the lung doctor stated that the COPD is truly "end-stage" and if the ventilator was initiated due to progressive decline in lung function (evidenced by more frequent flare-ups, requiring more support (like bipap), more frequent hospitalizations over last few months), then unlikely. For some tracheostomy has worked, but others still require a vent even with trach. Talk to your doctor(s) more.