Total removal of fiat from the society will do more harm than good.
No matter the level of technological development, not everyone will be able to embrace cashless transactions. And also, most services need to be paid in cash.
That is very true, also I dont think fiat will be gone complete, people have always trusted and will always trust something they can hold on and something that is physical, that is why gold has always remained valuable, if something replaces fiat it will certainly not mean bitcoin since the government doesnt want people outside the government to be rich, they will use their own little dirty system, so speaking of that let fiat just stay and let it live with bitcoin as a digital payment, it will do all good.
in addition to that, the use and exchange of something physical in doing transactions has been around since god knows when. It would be really hard to remove the aspect of physical trade to the human consciousness.