Imagine Miss World 2020 and 2021 taking place this year?
The two representatives can work head to head with each other for the fast track challenges. Then the 2020 edition takes place first followed by the 2021 edition where the new 2020 winner will crown her successor. It'll be the shortest reign ever but so worth it. The 2020 winner will of course, preside over the pre-pageant activities of the 2021 competition so the 2021 edition will take place about a month after the 2020 finale.
As for Miss International, this has been happening for a long time except in reverse. The Miss International Japan show is held a few days before the Miss International pageant where the new Miss International Japan is crowned. The ex-Miss International Japan will then compete for Miss international. All the delegates of Miss International participate in the Miss International Japan show.