Seeing them start the season very badly by experiencing two consecutive defeats certainly makes the rumor of Ten Hag's departure stronger, but I have not heard any definite news regarding when the rumor will actually come true, and for now I think it might be too early, because I also read some news that if in the near future the situation does not change, meaning that in the next few matches Manchester United performs worse then of course the rumor will most likely come true.
Of the several candidates you have shown, I think Thomas Tuchel is the most suitable figure to replace Ten Hag, we can see how his career was when he was still managing Bayern Munich who managed to defend the Bundesliga trophy for quite a long time, but I also heard that Tuchel now chooses to take a break first, but yes that doesn't mean it is impossible that in the end he could change his mind.