Barbie has more than a month of essentially no competition outside of Blue Beetle, so I don't know where you're getting the impression that Barbie's legs will suddenly start falling off a cliff.
Also "Last week was 43%" is not indicative of a pattern. In fact, it's not indicative of much of anything other than that Barbie has very above average legs (better than The Avengers' 50% drop may I add), especially given that last week was the most competition Barbie will likely face in its entire run. The established trend, or "pattern" is that with a lack of upcoming competition, we would expect Barbie's holds to improve in the following weeks rather than decrease.
As a final note you have also been guilty of consistently underestimating this movie, such as questioning whether 600m was locked far after most other people in the know had already accepted that to be the case.