If it got even close to that, transactions would dry up, thereby bringing the load on the mempool down. It’s theoretically possible that this happens in a very short time window but economically managed through supply and demand of mempool and txn space. Additionally, even dust can be insisted by grouping transactions.

So there’s an interesting future potential where 99% of transactions are grouped transactions and dust doesn’t matter because there will be services to help collect it back up and distribute over lightning. Miners could even provide this as a service.