Many, if not most, large corporations consolidate their internet connectivity into a very few and sometimes a single point. I was working recently with a large non-governmental organization who has consolidated all of their internet access for primary and field offices into their Chicago data center. It's a great model for using the Internet, not so good for incorporating the Internet. In the world of Cloud Computing the Internet is less an end point and more one of several intermediate points during the execution of a function. Public clouds must be accessible at all times from any location to be of value. This mandate implies there is no single point of failure between the corporation and the public internet. A new architecture is required with many-to-one access to the internet instead of a one-to-one model. If New York cannot connect to the Internet it cannot jeopardize the entire corporation. And remember that Internet backbones do go down and more likely will due to ever increasing loads in the foreseeable future. If the public cloud function leverages data within the data center the reverse is true; multiple paths provide redundancy. I'm sure some will argue with me but I cannot make sense of data travelling from Denver to Chicago just to gain access to the Internet; it's an archaic model at best.
The second major issue is existing Internet bandwidth will have to grow. At the same time as traffic moves to the Internet it will move off of internal WAN's. We've grown accustomed to cheap bandwidth but with the explosion of WiFi, the coming of WiMax, and the growth of rich media on the Internet I expect those days are coming to a close. I expect it will be cheaper to run over the Internet than through private backbones which will help drive us to a more federated model for Internet connectivity.
Finally security as we see it today becomes problematic. How do we sniff packets between a user and a cloud provider when the company has nothing traversed in between. Surely we could route users through the corporate firewall but again, this defeats some of the economic model of cloud. We need better tools on the client side to help us manage the security aspects of this federated model. I'm not saying there aren't tools today, but those tools need to improve their automated detection, recording, and reporting capabilities to prevent attacks both inside and outside the company.
I've noticed over the past ten years a change in approach to networking. In the past bandwidth was managed loosely to ensure it was adequate. We've really tightened it down and now we need to be asking our bandwidth providers to provide more virtualized options enabling the rapid, automated scale up and down of circuits. We don't want to leave the network out of the push to move from a fixed to a variable cost model in IT.