I think your post is insidious and pernicious.
The term "bottler" is used to describe someone without courage - Wilder is definitely not that - and well you know it - at least, it is obvious to most people.
I'll ignore your suggestion that if Wilder should leave it will make him a "bottler" and give my view.
First, I fully expect Wilder to ramp up the ante a bit in terms of trying to exert a bit of pressure into the Boardroom situation, because his success next season depends on that being resolved fairly quickly. I don't think he's being anything other than totally honest here and I'm glad he feels able to express that concern.
Second, I do not think for one moment that Wilder will be going anywhere this summer. I think he is 100% committed to having another crack at it with the Blades. But not only that, I don't think that he has got the profile yet, as a manager, that most clubs who may be considered to be "above us" in league status or other, are actually looking for. I'm pretty sure he will have, in time, but not yet. I think he's viewed as a promising manager, but one that has plied most of his years in the lower leagues so far and no track record outside the top 2 divisions, except for an encouraging season, this season, with Sheffield United. A lot of these "bigger" clubs are looking for managers with international experience as a minimum, which is why we've got so many foreign managers at the top level. So, although us Blades have a real insight as to what a fantastic manager Wilder is, our perception of his value isn't shared by many others outside the club at the top levels of the game. Not yet.
If "95% of Blades are "shitting themselves that he will go", then I must be in the other 5% then - because I have no concerns about that whatsoever.
He will stay. 100% certain. BUT...if he isn't backed in summer to go out and bring some quality into the team, and it could be expensive because we are looking at a new strike force for a start, plus some pace in the team, a left back and a centre half, oh...and a goalkeeper, then that could be the beginning of the end.
The actual "end" will come only when Wilder feels completely hopeless and helpless that he can't take this club any further.
And we are not at that point yet.