Knowing that you will hit the limit of the database in X years is different. Designing for the future is a horrible choice because where do you stop? Eg. Why

Knowing that you will hit the limit of the database in X years is different. Designing for the future is a horrible choice because where do you stop? Eg. Why are you sure that Cassandra, or whatever you choose, will be good enough for the future? Maybe you will need a Spanner type database or something even more big/consistent/feature-full.