I mean you just have to read my next sentence to know I don't think that? It doesn't have to be binary, I can think Ten Hag can still be a success and think someone else can be as well. I think Tuchel would at least structure us better and has a bit of pedigree. Not sure he's a particularly long term choice though, if we were to gamble on someone, I would like Iraola. There is absolutely no guarantee on him being any better than Ten Hag though and it's a huge step up.
There's no guarantees in football, full stop. All we know right now is we'll be facing a relegation battle soon if we don't act now. The odds of somebody else coming in and improving us is far greater than ETH turning it around now. On Tuchel, I just see him as a safe pair of hands until we can somehow hit the jackpot eventually.