> My thought was that we have code that is intended to be used for a > specific time frame. >
With your example of bloom filters, if that's on-disk then it is not to be removed. Specifically, code that is used in relation to a sstable format still listed in BigFormat.BigVersion (or BtiFormat.BtiVersion) must be kept. And there are no plans to remove it. See CASSANDRA-18312 There's been some deprecated since annotations added recently that imply a version of Cassandra is using a specific sstable format version. This is no longer true (see the storage_compatibility_mode yaml option). We are to consider past sstable formats are still in use in newer clusters. Though, the introduction of the option bound the lowest format version to 'nb' (see CASSANDRA-14227).
