Nobody can shut down Monero even if the price drops all the way down to $1 or even $0.01. OTC trades will still exist, DEX too.
I didn't mean it this way. The only way to shut them down would be to permanently shut down the internet. But even then, Blockstream has developed the Satellite which transmits the blockchain from space, without needing internet. That's unnecessary of course, because nobody can shut down the internet and even if they did, they would damage the current financial system too. Which of course is not their intention. I don't know who this "their" refers to, but you got the point.
As far as Monero is concerned, the only problem with the constant exchange price drop is that consumer goods are valued in FIAT, which is then converted to Monero, if you want to find a merchant that sells for Monero. So, they suffer from that. But if you can find a merchant that wants 1 XMR for product A, and doesn't care how much 1 XMR is worth in FIAT terms, then you can be confident that this merchant has deeply understood the value of Monero and Bitcoin. They are both P2P cash systems and should be treated as such!