People have said this about every social media app that became major for the past 10 years dude, Snapchat, Insta, TikTok, etc. If anything the batting average for social media companies that "make it" in the public's mind over the past decade is actually pretty good despite the field being heavily advantaged to incumbents by default. Snapchat is arguably the "least cool" on this list today and it still recorded MAUs in the 100 millions. TikTok ain't going anywhere.

More broadly, it turns out that once you are a company with access to billions of dollars, you will utilize that advantage to stay afloat. People still have some idea that if a business is outmanuevered/outgunned by a competitor, they will close down honorably, and that because teens are fickle they'll move on, etc, and this is all super unpredictable and unquantifiable and there's definitely not entire departments (with budgets as large as the GDP of Latin American countries) designed to account for this. You know, like the OP's leaks show Facebook has. Those rules might be true for your little mom and pop business, for your silly little thing. But not for these kinds of companies that can do an arms race for eyeballs to stay afloat, and they do not engage in the same rules as you.

You can rest assured, no matter how much it upsets you, that TikTok will be almost certainly be around longer in its current form than like 95% of the code written by people using this forum today, including your own.