first off, its not really feasible (there is no way in Gods green Earth that folks would allow the price to rise that much without taking massive profit waaaay before that level). but if through some Faustian deal we approached even a fraction of this price level, we are doomed. people would lose confidence in the asset completely, as it would be plainly obvious at that point that the valuation had no basis in reality or utility. prices that high and that quick would essentially make this so much of a gamble.
and we are already enough of that, as it stands.
I don't see the problem here. First if prices ever get to those values, that means we are getting into massive adoption of Bitcoin. Like hole countries doing it. If countries actually do that, then there is no point in exchanging BTC to fiat. Most people still only see the value of bitcoin as a way to buy low and sell high, but BTC it's not supposed to work only as a trading asset. If mass adoptions happens, then volatility will decrease and you will be able to just buy things with BTC. There are already houses being bought using BTC etc. That's the hole point of crypto, to work as a decentralized currency. If you can use it like that, why on earth would you convert BTC to fiat.
Not saying the price will go that high in just one year, but I would really like it to happen. If people just start to sell like crazy for profit, then they don't understand the purpose of BTC.