Sadly there's no new features being added to 1.12.2 but I'm hoping that when 1.16.4 modding is in it's prime, this feature will be implemented.

Idea:
Allow for users to make custom upgrades using different materials via a config etc. So for example if someone wanted a tier 7 upgrade then that would be possible by adding it via the config, although you don't really have to add the recipe yourself, people can do that with Crafttweaker or the like.

Reasoning:
Would be nice to have more tiers so then people can use them in progression packs like hardcore crafting or to just have more storage. Would be a cool addition to have so that players get the freedom to make a pack to their needs being it, personal or distribution use with friends or the modpack community etc.