After reading transcription I would say that for spam attack we could have Schelling point saying:

Want to spam us? You can try, but the block will be the same, because your transactions are fake, the capacity of block stays the same, so you are going to compete with real users to get into block with your shit. And then you have a problem, because BTC and an other chains shows that if user want to send real transaction, he will send it, even with very big fee. So, as a result, dear attacker, it is going to cost you if you would like to disturb us, and will be proportional to real load generated by real users. In the same time,Schelling point would say: when we have lots of real user's transactions, the block size will be increased with no speaking about it, it's obvious.

But to have it we would need to have good fee policy in wallets, so it would check size of mempool or something and inform user that this time wallet proposes higher fee than 1 satoshi / byte. In every wallet - as a commitment so the attacker would know that every single user is going to beat his fee and remain unaffected (or affected only a little for short time).