On the scalability issues of onboarding millions of LN mobile clients

The article discusses the future of light client protocols in blockchain technology, particularly within the Lightning Network (LN). BIP 157 implementation in Core is being advanced which provides an opportunity to reflect on the future of light client protocols. Although existing light client protocols for LN exist, their privacy and security guarantees may still be a concern with regards to implementation on the client-side. One of the bottlenecks in deploying more efficient tx-relay protocols such as Erlay is likely the number of full-nodes willing to dedicate resources to serve those clients. To address this issue, the author suggests dedicating more resources to increase the health and security of the backbone network by deploying more outbound connections instead of relying on full-node operators to service millions of LN mobile clients.Assuming 10M light clients each of them consuming ~100MB/month for filters/headers, that means asking 1PB/month of traffic to the backbone network. The author suggests using LSATs to add a lightweight payment mechanism by inserting a new proxy server in front of the filter/header infrastructure if the data starts being widely served over HTTP. Web-of-trust style of deployments should also be envisioned, where clients may be peers between themselves and the ones belonging to the same social entity should be able to share the same chain view without too much risk.The article also highlights potential issues of revoked commitments and other forms of unexpected behavior in blockchain technology, particularly within the Lightning Network. The author suggests introducing monetary compensation for servicing filters to address the problem of free-riding by light clients. This could be implemented within the watchtower paradigm, where another entity is delegated some part of protocol execution. However, there are concerns about how funds may be compromised by a watchtower or chain validation provider.Overall, the article emphasizes the need for further analysis and consideration of different approaches to ensure the security and efficiency of blockchain technology.