I'm not sure what "a marker" is and how to make it take 0 bits of storage.

This is an upcoming behavior in Valhalla which isn't yet a part of Java so there's nothing final. Currently Valhalla has primitive and value object types that determine identity behavior.

You mean non-nullable object types then. Which are faster and take up less space because that's how the hardware works :)

They're not faster for all cases. Near memory works great for some edge cases such as looping on an array of data in a block.

This is very much a special edge case. For many other non-benchmark situations this isn't so simple. If you add the overhead of memory copying and lack of identity things are more complex.