Big players making farms. Sure. Everyone can see that. Specialized silicon that would lead to 1 or 2 large players controlling bitcoin. No.
The intent was a decentralized peer-to-peer system. Failing to adapt the core to that end put bitcoin on a path of greater and greater consolidation that will eventually make it vulnerable to a number things and non-viable. It will be replaced by a version 2.0 that is peer-to-peer decentralized and probably has other fundamental innovations.
Remember there is an economic incentive for players not to collude and respect decentralization of the system.
Moreover you are also underestimating the prospects of commoditized ASICs and development of p2p mining pools.
Good diagram. Really helps to clearly understand your perspective and whats guiding it. Couple thoughts that I think may materially impact the degree of centralization differently than what you drew.
1. Why would a company making the best (most efficient cost per hash) sell that for less than what they would make mining themselves? The trend so far has been get public support to raise start up capital. If successful phase out public to maximize profits.
2. Assuming the best hardware is commoditzed and sold to the public; mining would still centralize around cheap power and cooling. Anyone paying $0.15+ in a hot climate is not going to be viable against someone paying $0.05 or even lower if subsidized like it is in some countries.
http://en.wikipedia.org/wiki/Electricity_pricing