2021 if you include the mass transit system and new station although the terminal should be completely finished around spring next year. By 2021 I am sure there will be other projects planned so it will depend whether there is a gap in the building work or the airport will just carry on building but what is going on this year and last year is the most intrusive part as far as passengers are concerned.
Work has yet to start is phase 2 & 3 which starts this spring but that is pure airside and involves new taxiways and apron extensions.