By "IBM Mainframes", are you implying Bitcoin will become obsolete in the future?
IBM mainframes are not obsolete, and they are still a multi-billion dollar business.
They are just no longer the "hottest thing" for most consumers, that's all.
I know altcoins have better features than BTC, but none can outmatch its level of security, reliability, and censorship-resistance.
As we've discussed in another thread, Bitcoin is no longer "censorship resistant" by itself (e.g. without mixers etc.) because of chain analysis. Criminals no longer use Bitcoin because of this--they will get caught if they do.
Even if it were, most consumers simply don't care about that, as is shown by the fact that almost all Bitcoin investors get Bitcoin through a broker or app, which is centralized.
Bitcoin is indeed very good for its stability as a project, and it's broad network. But lots of products can match that, and do. Again, 99% of Bitcoin investors rely on a centralized database governed by a single private company to hold their Bitcoin. That demonstrates they simply don't care about "decentralization" and all of that stuff.
Given that Bitcoin has come a long way since 2009, it's hard to imagine it will die anytime soon. Institutional adoption is increasing at a very fast pace. What I don't like is that most people are relying on BTC as a store of value than a currency. It will never be able to replace Fiat this way.
Bitcoin will never replace mainstream daily transactions, and it was never meant to. Such a currency would need to scale to levels thousands of times larger than Bitcoin, and the blockchain architecture is
intentionally slow by design. The problem it was trying to solve was ""censorship resistance"", not trying to be a common payment method.
If Bitcoin survives, I hope it never becomes centralized. We should stop selling our BTC to institutional investors if we want to encourage self-custody. If they acquire all of the BTC, then you'd need to trust a middleman to buy/sell the cryptocurrency (something Satoshi meant to avoid in the first place). The future is unpredictable, so lets hope for the best.
If people did what you are suggesting, the price of Bitcoin would drop by 95%, so... people aren't going to do what you are suggesting
.
Bitcoin is going to be fine, but it's not going to be the last word in digital currency, that's all. There will be new things that will be even cooler than Bitcoin.