However, it will be up to the UK government to decide what it puts in a new Government of Wales Bill which would be needed for any substantial changes to the assembly's powers or structure, including new members.
The assembly would, in Mr Donaldson's scenario, work in a committee-like structure to advise the ministers of the Northern Ireland Office, but would not have administrative powers or make executive decisions.
Committees have been described as the "engine room" of Assembly scrutiny and for weeks now, the cross-party Business Committee has been locked in discussions about their future structure.