The same way capitalist concentration made building a small business very hard by the start of the 20th Century, the same process is taking place right now with the Internet. We usually don't notice or even like it (why, isn't it great to have every service in the same place?), but it is a tendency. Many arguments in favor of the small business and the virtues of free competition that were used back then are being used now by this post. The post even acknowledges that "the world isn't flat", but presumes the Internet needs to be, as if it was isolated from the rest of the system.
Even if net neutrality were approved, I don't think that unless there are other technological revolutions that open new sectors up like the PC or the Internet were, that subdivisions of large companies will be responsible for most new stuff, taking the most of the market for itself anyway and making competition harder, as we can see today in many ways. It'd just be a (very positive) way to preserve the current state of things a while longer, but not something capable of keeping the Internet "flat" in the long term.