The surviving NFT projects that will require no active maintenance in the next 10 years will be the ones who fully dedicated to on-chain only (cryptopunks, chainrunners, etc).
Unless there is an active community that maintains its strength during market cycles (like BAYC), current NFT project death will be 95% over the next 10 years, just like a start-up.
Imo the point of the blockchain is that it can do many things (such as payments, storage, immutable records) all in one place which will lead to an overall increase in societal productivity.
In the case of your diploma, it's true that there are other ways to have a distributed immutable ledger that contains a signature leading to the diploma. However, by having one agreed upon global ledger for any university to upload to with a proven statement of authenticity for the degree, you then have the ability to build technologies on top of that massive ledger that would have been much, much harder if each university decided to host their own distributed ledger.
A simple example would be a hiring company (like lever.co) being able to verify degrees instantaneously on-chain instead of requesting a proof of degree from the university. This request for a proof already happens in real-life and requires a relationship between the university and the hiring company. The blockchain can then come in and allow companies to verify degrees in seconds, rather than days, leading to an overall increase in productivity.