some node centralization Vs settlement layer prohibitively to expensive to use by everyone
i'll pick full node centralization....
Why does it have to be either/or? Why not aim for a balance where the costs for the settlement layer will increase slightly and the resources required to run a node increase slightly. Sacrificing one to bolster the other will always leave someone at a disadvantage, so if the costs have to go up, it should be spread as equally as possible between the two.