Bagso
Perhaps but remember airlines will be prepared to wait for LHR capacity, they wont wait for MAN to produce a terminal which will likely be at full capacity when its completed.
2 -3 years (construction) is lots of time and while it would be a complete disaster for passengers/airlines, it would be better long term. Perhaps if MAN cut some parking spaces and erected a tenp terminal or boarding gate area it would do the job. If you were over in DUB when they were constructing piers it worked perfectly well.
10 years is a complete joke.