Either way, it is clear that the Bitcoin network does *not* provide the level of settlement speed that the major currencies' RTGSs provide.....
It's important to point out that this is of zero relevance to any individual, as they are not a bank, and thus have no access to any currency's RTGS system.
Not quite.... individuals don't have *direct* access to any currency's RTGS but they *can* make use of them indirectly. e.g. for house purchasing in the UK, it is normal for a purchaser to transfer their deposit over CHAPS to the lawyer acting on their behalf. The need for near-real-time settlement with finality is key.
The reason I brought this up is because I sense discussions about settlement speed, etc., in Bitcoin are based on a misunderstanding of how other currencies work.
To my mind, the Bitcoin network is an RTGS, rather than a DNS (gross settlement, settlement in "central bank money"*, finality, etc). However, discussions on this topic talk about use-cases most usually addressed with DNSs (e.g. retail payments, online commerce, etc, etc).
Now, nobody would ever suggest using Fedwire for every credit card transaction in the world but people *are* implicitly suggesting that, should Bitcoin gain widespread adoption, every single transaction (every pint of beer, every pizza, every coffee) would be passed over the Blockchain.... in other words, there is an implicit assumption that Bitcoin (an RTGS) will gain widespread adoption for use-cases currently solved with DNSs.
It's just not obvious to me that this is the right answer.
Sure... a Deferred Net Settlement for Bitcoin using a traditional centralised architecture would be unattractive -- but one could easily envisage an architecture where low-value transactions take place on "auxiliary" side-chains before being periodically aggregated (and hence settled) net on the main BTC chain.
* Clearly, there is no "central bank" in Bitcoin but the entire network can be seen as analogous to one (it controls the money supply, provides regulation (difficulty adjustments, rejection of invalid transactions, etc), etc, etc).