"supported_enchantments" data component.

Currently, datapacks can add enchantments and enchant tags as they please. Each enchantment is in a different tag. However, no heavily modified items can have their enchantment table changed without changing the base item.
The suggestion is that a new component be added called "supported_enchantments" or something similar, which bakes which enchantments can be given to the item by enchanting tables, anvils, and the /enchant command directly into the item. This way, the possible enchantments can be changed to a different enchantment tag.

For example, /give @s minecraft:diamond[minecraft:enchantment_table=["minecraft:exclusive_set/damage","minecraft:exclusive_set/boots"]} would give a diamond that can be given either damage enchantments or boot enchants.

To add onto this, since the "enchantment" tag folder is used for something else, there could be a new folder called "enchantment_tables" or something of the like that completely replaces the need for the "primary_items" flag. Either way, compatibility with datapacks would be very important.

Say you have a datapack that adds a warhammer, and you want that warhammer to be compatible with Breach, and all the other damage enchantments. With this addition, you could have something like
/give @s minecraft:iron_sword[minecraft:supported_enchantments=["foobar:warhammer"]}

along with a enchantment_tables list that includes both damage enchants and specifically breach.