Basically the article says that the Bitcoin blockchain won’t scale for the entire world population to use it. It will so much not scale that even “offchain” solutions like Lightning and Ark will not scale and they basically lose usefulness as more adoption happens and fees rise.

A thing I haven't seen much discussed but that seems important: fragmentation of the utxo set when there are 100x more users. Utreexo is one way of approaching this, but I'd be interested to be pointed to discussions on the topic, especially ones that do computational modeling / simulations.

Imagining high on-chain fees + utxo fragmentation into quasi-dust is scary.