If you push the block size upward, there is little change compared to today - individual miners still choose what pool they direct their ASICs to. It cant be any worse.
Well, while I'm not sure what might happen with mining I'm certain that the number of nodes will shrink or the concentration in datacenters will increase. This is not good.
Node numbers has nothing to do with individual miners directing their ASICs to pools, exactly the same way as today, nothing change for individual miners here. Also arguing change limit to 2MB (or 4MB) means number of nodes have to decrease considerably is wrong, there is scientistic study I saw recently it might decrease the node count by up to 10% - you will not notice such small change on decentralization (btw thanks to Bitcoin Classic we are already up by 30% in 1-2 months)
On the other side with artificially keeping small blocks, unable to use onchain Bitcoin transactions is definitively increased centralization, as users have to use centralized offchain solutions (similar how bank or paypal works).
Completely wrong:
1) On-chain remains decentralized (nodes are cheap to run).
2) Decentralized second layer solutions will exist (LN).
1) with 2MB (or 4MB), nothing changes much here
2) second layer (LN) does not even exist currently, so pointless to argue whether LN become decentralized or can be used only in centralized maner as seems today