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People will still mint, trade, send, receive their dick pics and fart sounds on-chain on the Bitcoin blockchain simply because "they can".

Of course. But then, people willing to use Bitcoin as a P2P money will simply move to other subnetworks, while leaving on-chain spam, where it currently is. And then, you will have a choice: use the current client, and process all of that money-unrelated spam, or upgrade your client, and focus on monetary transactions.

So, it is only a matter of making enough people angry enough, to develop that kind of solutions. Satoshi was angry, because of fiat currencies, and that pushed him to make Bitcoin in the first place. If fiat currencies would be better, then Bitcoin wouldn't exist, because then, there would be no need to make it (which you can also read directly in the Genesis Block, how "second bailout" was literally the input to create Bitcoin).

And if NFT enthusiasts will abuse the chain more than they should, then some developers can be pushed to their limits, and make a money-only-based network, on top of Bitcoin, which would be designed, to explicitly exclude other use cases. Technically, it can be done, it is only a matter of pushing people enough, to start discussions, similar to what I linked, and bring changes like that into reality.

Also, as long as spammers are strong, such changes would be just optional. I don't want to force everyone to follow my rules, but note, that ideas like dropping UTXOs can come from developers as well. And in that case, they can make it mandatory, by turning them into soft-forks. And then, I don't know, what will be the end result, but I guess the optional path will be taken anyway, and just P2P money enthusiasts will move to their own subnetwork, where they will focus on money, and everyone else will use the official version, which would allow a lot of spam, and would have heavy requirements to run a node, if you compare it with other alternative, more spam-resistant clients.

For now, my plan is to still stick with Bitcoin Core, but as you can see, by pushing more spam on-chain, many people can be convinced to use a different implementation, or to run their own tools on top of Bitcoin Core (which is for example how Paul Sztorc wanted to introduce sidechains, by making his "Core Untouched Soft Fork" client). If there will be more spam, then such things will just happen more often, and some people will start using different implementations, to make Bitcoin usable with lower resource requirements, and fight with centralization pressure, made by spammers.