As for on-chain size increases, those need to be preceded by study into off-setting the additional processing burden higher blockweight limits represent. Segwit is somewhat of an example; allowing signature hashing to scale linearly mitigated (but did not offset) the increase to a 4MB block limit.
Have there been any noteworthy studies on the potential effects of bigger blocks since the IC3 and Bitfury studies? I suppose that data is a few years old now.
My biggest concern at this point isn't the marginal nodes and miners that couldn't keep up with the network. I'm much more concerned about the propensity for any hard fork to cause a permanent split with multiple resulting networks. Segwit was a one-shot deal; there's only so much you can do by discounting witness data. We can further optimize transaction size, but eventually, the notion of a hard fork block size increase will rear its head again.