Spiritbonding and Non-convertible Equipment

Every piece of equipment in the game has a spiritbond gauge. But, because the intention for full spiritbond on gear is conversion into materia, and due to restrictions on which gear can be converted, a large amount of equipment receives no advantage from 100% spiritbond.

Furthermore, currently the majority of convertible gear is crafted, yet with materia becoming widely available from sources other than spiritbonded gear, spiritbonding crafted gear may become obsolete. (In battle gear terms, of course.)

Since the newest high item-level equipment has materia slots, could it mean that more non-crafted equipment will be convertible in the future? Could spiritbonding be made to have some effect on currently non-convertible gear instead?

For example, achieving 100% spiritbond on non-convertible equipment might improve its durability, or activate a latent effect such as a small stat boost or a set bonus, or even just a minor cosmetic effect. Perhaps it could even improve the effects of melded materia.