Difficult. For one because because PS4 isn't done yet, so we don't even know where PS4 will stop. Assuming it'll be around GameBoy-level (~120M), it's still difficult because I'd say Switch has a change to finish around a similar point. So it might as well not pass PS4 at all, or it does so at the tail end of its life, which is also unknown.
EDIT: Voted Second Half of 2024, since if Switch gets to around 120M it should be by then.Last edited by S.Peelman - on 11 January 2020