Isn't this all moot in a (almost guaranteed) future where fees are very high? Genuine economic BTC transactions will always out-compete "data storage" transactions.

Proponents of Bitcoin as the global reserve currency are predicting per-transaction fees of $10k+ (within the range to physical gold settlement costs), for late-stage Bitcoin network. No ordinals, inscriptions, runes, etc is going to exist in the mempool or any blocks at those prices.