yes
more data needed for full node = less people running full nodes
Ok I follow you so far but there seems to be countervailing forces as well.
Right now nodes are run via altruism. That means only larger BTC holders will run one because the only reason to do so is to protect your investment by helping support the network.
I for example have finally accumulated a modest but large enough position in BTC over the last year or so that it makes since for me to start a node and I am looking into how to do so. Had BTC remained at $250 that probably would not be the case.
Will SegWit + 2Mb make it technically unfeasible to run a node from my home? If not I don't see the problem. As BTC grows in value the number of people who's holdings cross the node setup threshold will increase leading to more nodes as long as the overall resources demanded remain within the ability of the hobbyist.