> Bitcoin is and always will be limited in capacity - transactions may not
> confirm in a reasonable about of time because of high-demand and/or DoS
> attacks.

I agree in the general case, but I was talking about the mobile wallet case specifically (i.e. people who are sending money between themselves or making small purchases of physical things). I think Bitcoin should be able to scale to handle these sorts of ordinary every-day transactions. Where I’d expect to see transactions falling off the edge is in more specialised cases like very small single micropayments, or “optional” internal transactions like mixing/re/defragmentation of wallets that don’t correspond to an actual payment. Those sorts of transactions would I guess be the first to go when faced with a sudden capacity crunch, but they wouldn’t show up in a mobile wallet UI anyway.

> re: merchants paying tx fees, child-pays-for-parent is inefficient

I know the existing code is, but is that fundamentally the case or just how the code has been written? I haven’t looked at this issue much but I know you’ve worked on it, so I’m curious to learn about why it’s inefficient and whether there are any fixes possible.