My best guess is, a lower denomination comes packed with a lower fee as well - as in, you could pay fractions of satoshis per byte (and I think that already could be done without further changes to BTC's structure). If BTC gets to an insane price range such as millions, I doubt the network will still "fight" over the range of sats/byte we currently have as we speak. The more BTC'll be priced, the less sats people will pay for txs - and I think that's quite logical. It'd make no sense to pay hundreds/thousands of bucks per tx, even if we're talking about millions.
Good point. Since Bitcoin is divisible to 8 units, there might be no need to increase the max supply in the future. If prices go all the way to the moon, people might be transacting with "satoshis" instead of a Bitcoin. In the future, it's expected for Bitcoin to boost its transaction capacity like never before. It's hoped that the Lightning Network gains massive adoption in the mainstream world, making "satoshi" payments (micropayments) practical once more.
Based on my calculations, there will ever be 2,100,000,000,000,000 satoshis in existence (21 max supply 1 satoshi). That's plenty enough Bitcoins for anyone to use worldwide. In case fees become too high relative to Fiat, people will pay less for their transaction to go through the Blockchain. That is of course, if people know how to set their own fees in their wallet of choice. With so many Bitcoin-based forks available today, the max supply of 21 millions coins has been virtually expanded. The main Bitcoin blockchain might be able to last for long with its hard-coded maximum supply for the foreseeable future. Future generations will have to see if Bitcoin will be able to live up to the standards after the year of 2100. Just my thoughts
