There are few flaws, especially on sharding (which you probably already know). But my biggest concern are :
1. How do we categorize address to different network?
2. How will it works when you have addresses on different network and you plan to make payment to multiple address from different network?
Additionally, IMO this sounds like we have
n different bitcoin coins.
Edit : adding reference and similar proposal
https://github.com/ethereum/wiki/wiki/Sharding-FAQshttps://bitcointalk.org/index.php?topic=5060909.0