This whole question is wrong because you are only focusing on a tiny insignificant thing (fees) while there are a million different things that are much more important. For starters in 100 years from now, Bitcoin may not even exist. The cryptography used in Bitcoin is going to will have been obsolete for years by 2140, so by then Bitcoin either will have had significant changes (hard forks) that would fundamentally change it or a more probably thing is alternatives will have been invented that replace Bitcoin.
As for fees, people don't tend to use a payment system that is expensive. If that becomes regular in Bitcoin, it would kill it. That means it stops being used by regular people for payment and it will lose its "hype" and subsequently there won't be any reason for scam attacks such as Ordinals to be using the "bitcoin name".
Disagree. The fee structure is a fundamental pillar on Bitcoin. Without that incentive there is no one to process blocks which contain transactions. As far as the cryptography being compromised, that is a problem that everyone will face eventually. And yes, that may be the first time a hard fork has 100% agreement, I mean that is a clear Schelling point in benefit of all Bitcoin holders.
As far as high fees, people will just use 2nd layers. Unless some impossible to imagine alternative is invented that is so good that people want to migrate their money there, Bitcoin could perfectly exist in 100 years. This is a software, it's a digital asset, it's not some physical thing that has to be replaced. It's interesting to think about the far future and see what will happen. I believe BTC is here to stay unless a major discovery is made that like I said, invents something that we cannot even imagine now.