Wouldn't (almost) everybody use very low fee because of that? and thus, wouldn't it lead to make a heavy mempool?
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Heavy mempool is already here, and not with regular transactions but with shitcoins spamming. People who want to buy cars, coffee or gift cards are not going to wait 6 months for a transaction. I'm not optimistic about the disappearance of the BRC20, I think that this scam will remain, that nothing will be done to prevent them from causing harm by permanently obstructing the blockchain. With a system where the priority of a transaction would also be based on its creation date, the 1 sat/vBs would at least have a chance of being integrated into a block, even if it takes 6 months or more. Right now, we're on the way to ensuring that tx's below 5 sat/vb recorded at the end of 2023 will never be included in a block.