The more likely scenario is manipulation by banks and wall street in order to try and accumulate more coins for cheap. Depending how desperate they get, determines how desperate their measures go both within the Bitcoin market and outside of it. This is nothing new, during earlier times where people and entities competed/fought for rule over assets and commodities, banks and wall street were known to play dirty. No different this time.

Centralization through ownership of supply (which would effect the market, not network) is a possibility if people sell to them. Centralization of the network is a much larger and more complicated task, requiring control over territory and influencing/controlling both local and international mining operations.