Assuming usage of OP_RETURN as the garbage can for non-financial data that would otherwise go into the UTXO set is naive.
First, it's more expensive than inscriptions, control block embedding and other techniques.
Second, you're expecting developers of ordinals, inscriptions, stamps, brc-20, etc to *change* their protocol to accommodate. There's zero evidence this is going to happen.
Third, you're assuming that these are people that want to act as good stewards of the Bitcoin protocol. They spam specifically to hurt Bitcoin. They've demonstrated this by spamming in the first place. That's like asking malicious spray painting vandals to paint a particular wall that's easy to wash off. Again, no evidence that this is going to happen.
The logic is misguided and makes unfounded assumptions.