I'm specifically wanting to discuss the possibilities of developed countries only having access to the hardware and bandwidth capabilities that the Blockchain may require in the future. As the Blockchain gets bigger through more transactions and more blocks stored within it running a node may become limited to developed countries alone.
I'm not sure what the estimated size of the Blockchain when all the Bitcoin has been mined but judging by the size of it now and if it did become mainstream then we would be seeing exponential growth which will lead to more centralization because not everyone will have to equipment or internet capabilities to run a full node.
This may mean that full nodes which we rely on for the security of the network will be controlled only by wealthy individuals or those from developed countries. At the moment almost everyone in the world has the requirements to run a Bitcoin node. Hard drives are cheap and bandwidth is only the limiting factor around the world. Even then people just download it over the course of a month or something.
However if the Blockchain is exposure to the mainstream how are we going to make sure that the network remains decentralized? Especially when Bitcoin rises to petabytes instead of gigabytes. Are we solely relying on the fact that technology should advance at the same rate as the Blockchain growing?
Here is what Satoshi had to say on this matter.
The current system where every user is a network node is not the intended configuration for large scale. That would be like every Usenet user runs their own NNTP server. The design supports letting users just be users. The more burden it is to run a node, the fewer nodes there will be. Those few nodes will be big server farms. The rest will be client nodes that only do transactions and don't generate.
Besides, 10 minutes is too long to verify that payment is good. It needs to be as fast as swiping a credit card is today.
See the snack machine thread, I outline how a payment processor could verify payments well enough, actually really well (much lower fraud rate than credit cards), in something like 10 seconds or less. If you don't believe me or don't get it, I don't have time to try to convince you, sorry.
http://bitcointalk.org/index.php?topic=423.msg3819#msg3819