Trustless self-custody isn't an issue today. Bitcoin can handle the present demand with room to spare (arguably too much room to spare, given the flagrant waste by spammers creating new, bigger problems).

What is an issue, is that the demand isn't there: people are all too happy to trust custodians, especially when faced with the challenges of self-custody.

Those problems are largely the result of big blocks and spam, and addressing those issues should be the immediate focus of developers looking to make Bitcoin successful.

The lack of attendance at "OP_NEXT" was, at least in my case, because it was a scamcoiner conference aimed at attacking and destroying Bitcoin.