I'm not sure why you guys are now speculating of a future in which a 100k increase of the block size limit is possible. You are not factoring in computational limits into this. Even if storage and bandwidth were very cheap (affordable for such blocks) and everyone had connections that could support them, there are still computational limits. Validating such a chain, or syncing up to the network would be a nightmare (you would likely never be able to catch up)
I agree with you in general that there might be a lot of other factors making such scale-ups simply impossible. Though the required capacities and speeds might still be technically achievable in the future, exploiting them would nevertheless be a terrible waste of resources, anyway. Regarding your point specifically, that is, computational limits, I think that these can be overcome eventually by using highly specialized "transaction validation" hardware...
Just like ASICs (or whatever) are used for mining coins today
And we would need such speeds across continents, dedicated entirely for the support of Bitcoin infrastructure
The problem with increasing the block size is not only the transfer speed
It is easiest to prove