for the short term there will be a big dump. but no long term impact. I don't think they're all stupid, they will sell gradually and announce all of it after they finish selling it. so no one realizes that they have sold their bitcoins. and when the announcement is published there will be a momentary dump.
Elon is too smart that he can create hype to make the market in his favor. Even many thinks that people lose trust in his tweet or perception in crypto ideas, many individuals who are still not in crypto believes in him and willing to take risk to follow him without guarantee of profit, which sometimes it will only lead to Elons profit. We just need to plan on our own since we can’t control them especially those who we consider whales, we will be affected in what ever moves they do so we just need to plan and be active to save our profit when times like this happens.