This kind of thread would probably belong in the dev and tech sub or the alternate clients depending on the specifics
Actually on second thought, this would have nothing to do with the client satoshi designed, so it would belong in alternate clients.
This is layer 2 technology. It has everything to do with the Satoshi client indirectly, and is an extension to Bitcoin Core. There will be a lot of questions and a lot of people asking about how to move Bitcoin to the secondary layer, should we finally be getting SegWit activated. You can already see topics about lightning popping up, even if it only works on testnet so far.
It will be a mess to coordinate anything layer 2 wise if there is no forum for it.