Just like 21 million coin limit is also an arbitrary limit of human imposition. The idea behind it being a simulation of gold's supply is irrelevant, what matters for all intended purposes is that it became an immutable trait of Bitcoin due the game theory involved, just like 1 MB blocksize has become an immutable trait of Bitcoin due the game theory involved, this is called protocol solidification.
At it's inception, any values would have cut it, since satoshi was calling all the shoots. Once the creature was alive, he disappeared, and im sure he was smart enough to know (either planned or in retrospect) that those values would never change. It couldn't go any other way if the project is indeed decentralized. This is the fact only for Bitcoin, no altcoin meets the criteria, which is why all altcoins are overpriced and Bitcoin is undervalued, at any rate.
I'm don't think satoshi planned for the 1mb size to be immutable. When Garzik suggested a patch to increase block size, satoshi stated this can be phased in later. I'm not certain the segwit work around was quite what satoshi had in mind.
https://bitcointalk.org/index.php?topic=1347.0What satoshi said doesn't mean what satoshi knew. He may or not have known that 1 MB blocksize would eventually become yet another value which becomes immutable due protocol maturation, what matters is the results, and the situation is clear: Reaching wide consensus to raise the blocksize at this point is basically as controversial as raising the max cap. You can find arguments on both sides, which as a result, the status quo prevails.
satoshi did at least predict there would be an opposition to raising the blocksize way before the blocksize crisis happened:
Piling every proof-of-work quorum system in the world into one dataset doesn't scale.
Bitcoin and BitDNS can be used separately. Users shouldn't have to download all of both to use one or the other. BitDNS users may not want to download everything the next several unrelated networks decide to pile in either.
The networks need to have separate fates. BitDNS users might be completely liberal about adding any large data features since relatively few domain registrars are needed, while Bitcoin users might get increasingly tyrannical about limiting the size of the chain so it's easy for lots of users and small devices.
He knew. And so, he disappeared when Bitcoin took a life of it's own (impossibility to reach consensus to change it). Contrary to the idiots that think Bitcoin is doomed because you cannot buy coffee on-chain, that realization was the fact that Bitcoin was a success.