I disagree. The ability to reach consensus within a community does not necessarily imply centralization.
As a self-described fairly intelligent tech person, the blockchain and its working is still fairly magical to me, so answer me this:
Would it be theoretically possible for big players on the market (read EvilCorp) to push the market over to a fork by convincing enough of its cronies to make the switch?
I'm assuming what you mean is that market consensus is (at least) 51% of the market accepting the fork as "the truth" in terms of value by making further business there instead. Or would it not even require 51% but merely (for example) 20% of the capital that covers 80% of the transactions?
I also assume anyone that wanted could still stick to the former blockchain as long as it has other participants to deal with?
Am I wrong in expecting a synecdoche to the current "real world economy" within cryptocurrency that it loses its democratization when the top X% can force for example a fork?
If the protocol developers and exchanges switch to a fork, there's very little the community can do.
Sticking with the former chain is difficult because 1) everyone else is calling a different chain "Ethereum" therefore you probably need to change your name to something else, 2) You need to be concerned with mining attacks
In this case the sentiment among actual ETH holders is ~ 85% in favor of the hard fork. Check http://carbonvote.com/ (it's not a binding vote, just an indication showing which way the wind blows).