Mid-December 2020 does seem like a great spot for GvK, especially if the major competition is just WEST SIDE STORY and CRUELLA DEVILLE. WWS and CD are different enough from GvK that they shouldn't overlap their audience pools very much.
Right now, I think every movie releasing in the month or so after (even a month before) AVENGERS: END GAME is has done lower than it might have because END GAME has raked in so much potential box office. END GAME was always going to be big, and has been huge box office draw -- but movie trips have become increasingly expensive with an average $9 and change per ticket in the US before any concession purchases (which can easily double a trip's cost). And with real people considering their budgets a second or more time watching END GAME meant not watching SHAZAM, GODZILLA:KOTM, MIB: INT, DARK PHOENIX, etc. while those movies are in theaters.
Considering the lower than expected box office takes for the other movies I mentioned, I think G:KOTM has done surprisingly well against the DIsney combo of END GAME and ALADDIN.
Who knows what evil lurks in the hearts of men?