Although this is too far away to determine now, I think there will be need to increase Bitcoin's max supply in the future. With increasing adoption of bitcoin over the coming years, with a large percentage of these people keeping bitcoins as a store of value and not as a currency which would keep it in circulation, there would be need to increase the limited 21 million supply of coins into circulation.
This might invoke the need for a much better and higher technology and codes, it will inevitably have to happen. Besides, technology is evolving and we will get to that bridge where we've exhausted the limited coins, we'll cross it.
Honestly, I think Bitcoin is (and will do) fine with a max supply of 21 million coins. That's largely because Bitcoin is divisible up to 8 decimal units. There are 21 quadrillion satoshis for anyone to use in the mainstream world. That's more than enough to satisfy the world's population. Increasing the supply to a higher value will do more harm than good to the price of Bitcoin on the market. Even if Bitcoin's supply remains the same, it has already been theoretically expanded by the number of Bitcoin-based forks that emerged since 2017. Bitcoin Cash and Bitcoin SV both have a max supply of 21 million coins with the same protocol as Bitcoin (only with a few minor modifications). Bitcoin holders prior to the Bitcoin Cash hard fork in August 2017, have now doubled their coins on competing blockchain networks. If we were to perform calculations, Bitcoin has effectively increased its max supply to 63 million coins (which is the sum of Bitcoin, Bitcoin Cash, and Bitcoin SV's 21 million coin supply).
If prices become a lot higher than what they are right now, we could expect people to deal with "satoshis" instead of a Bitcoin or 1/10 of a Bitcoin. With the Lightning Network already gaining traction, it's possible to send satoshis across the blockchain at a fraction of the cost. At least, we won't need to worry about Bitcoin's max supply during the course of its lifetime. Just my opinion
