On Fri, 30 Jan 2015, Nick Simpson wrote:

> This has been discussed before. I believe most people don't expect Bitcoin to replace all of the various methods of payment.  Scalability is
> always a concern, just not to the level of  Alipay this year (or the next or the next for that matter.)

Yes, that about summarizes it.

The block chain is a single channel broadcasted over the entire 
world, and I don't believe it will ever be possible nor desirable to broadcast all the 
world's transactions over one channel.

The everyone-validates-everything approach doesn't scale. It is however
useful to settle larger transactions in an irreversible, zero-trust way. 
That's what makes the bitcoin system, as it is now, valuable.

But it is absurd for the whole world to have to validate every purchase of 
a cup of coffee or a bus ticket by six billion others.

Naively scaling up the block size will get some leeway in the short term, 
but I believe a future scalable payment system based on bitcoin will be 
mostly based on off-blockchain transactions (in some form) or that there 
will be a hierarchical or subdivided system (e.g. temporary or per-locale 
sidechains).

Wladimir