I generally agree with your points about the advantages of NWC and focusing development efforts there. However, having personally run a self-hosted Bitcoin node and Lightning node, and connected them to my phone's Lightning wallet via NWC(thanks #alby), I'm skeptical that the average user would be able to do this. People simply won't use something if it's inconvenient.

While developers will undoubtedly work hard to improve the user experience, true usability—specifically, the ability for a user to reliably receive payments even when their phone is idle or they're asleep—requires the Lightning node to be running 24/7. It seems difficult to achieve this without the help of cloud (i.e., custodial) services.