The limit could be too low. Ridiculously high may not be high enough.
Bitcoin could become wildly successful much sooner than expected.
I agree. And the framework I posted earlier accounts for this.
My bias is to "get big fast"
Mine is too. But it is entirely possible that exponential growth over the next twenty years will simply not be fast enough. If you look five years out, for instance, we would be at 67 MB per block, which is roughly 20 million transactions per day. Assuming some small fraction (1%) of people in developed countries are using Bitcoin regularly (every other day) by that time, this limit would create significant pressure for adoption of sidechains or off-chain services.
Once you assume sidechains, what is the marginal benefit of maintaining a node for a huge main blockchain that consumes half of your internet connection?
My point is, probably most of the scaling will be done on a sidechain maintained in datacenters. And probably you won't care about that, if it's just used to store your lunch money. But you
do care about the main chain, even if you only use it once a month. So that's what you want to be as decentralized as possible, running on as many nodes as possible, even if it still has to grow quite a bit in order to be accessible. There's no ideal way to have a single chain that grows and remains decentralized. But two chains could do it.