If you want data then define a schema and write/read your data. Serialization should really never be used and certainly not for long-lived data storage.
There is one place where serialization becomes useful and that is for storing objects off-heap, IPC, and for short-term storage (ie snapshots like Android's parcelable). For these cases I'd like to see the JVM embrace not just immutable value objects but full-fledged structs that have a well-defined memory layout. You can do this today using off-heap Buffers and interfaces but language support is always good so there's a universal standard that everybody can build upon. Once that's in place there'd be no need to ever use serialization.
That said I can't imagine Oracle will simply remove support object serialization. It may be kicked out of the "core" JDK and become an optional module. The classes may be deprecated. But the functionality likely isn't going anywhere in the next ten years.
Even if they did remove it nobody should be using the standard object serialization anyways. If you're going to use serialization (and you shouldn't) then you should absolutely be using FST [0].