So I played SevTech for a while, but at some point I got fed up with the low frames I was getting on my laptop. I started adding some performance improvement mods and when that wasn't enough I started thinking: what if I just remove all the Age 4 and 5 mods that I might never get to anyway, but it still wasn't enough. However that left me wondering: if I remove the end-game the mid-game goals don't really make much sense any more. Some mods like Immersive Engineering I really want to play with, but if the end result is getting plastic and not really having anything to use it for it feels kinda pointless.
That got me thinking about why I played Minecraft at all and although I generally enjoy the experience, it's usually takes some new gameplay element and an idea for how to use it to get started on a new world. However problem with many mods is that, no matter how cool they are, if they won't bring me any closer to realizing that idea or make the experience more enjoyable in general, I never end up playing with it.
There's just so many cool mods out there and only so many things a mod can do to improve the player's experience that there's a lot of overlap and I think that's where SevTech shines. It packs a ton of cool mods while having little content overlap, accomplished by a progression tree and buffing/nerfing some mechanics through configs. However this is a lot of work (not just writing all the scripts, but also play-testing) and the result it monolithic: you can't take some mods out that you don't like anyway or that your computer can't handle and you can't add extra mods that you feel are missing.
So how can we create modpacks with as little as possible content overlap (no parts of a mod are useless because some other mod provides an improved or easier to get version of the same mechanic) and a common end goal that requires something of each mod, while keeping modularity that allows players to tweak it to their own liking, without too much work on the creator's or player's side?
In short: small mod packs that are confined to their own dimension and make it easy for the player to combine these into a full pack.
The mini-packs are confined in the sense that their crafting mechanics, mob spawning, etc, only work when the player is in the dimension specified by the pack (just like how SevTech confines mods to ages), meaning that the player will have to find a way to survive/progress within each new dimension and use much more of the featured mods then usual.
The player would access the respective dimensions from a central hub, but they would only be allowed to take a limited number and type of items with them (this should be configurable in the mini-pack and easily editable by the player in case they need to resolve some compatibility issues), for example a food item and a tool.
The player can teleport back and forth between a mini-pack dimension and the hub at will, but they won't be able to take items from the mini-pack dimension with them or change the items they can take with them until they reach the end-game of the mods in the mini-pack and craft some specific item or get an advancement etc. This should be configured by the mini-pack creator and should somehow contribute to the common end goal of the full pack (more on that later).
When the player has completed the mini-pack, the transport limitations are lifted and they can move whatever infrastructure they created in the dimension to the hub if they wish, so they can enjoy the combined power of the "unlocked" mods in full glory and take better/different items with them to the next dimension.
When the player completes all loaded mini-packs they should be able to craft some kind of "you win"-item (maybe creative/avaritia stuff), or even cooler: gain access to an ultra hard dungeon with a boss where they can use all the equipment they created during their journey.
Possibly the player could be provided with an interdimensional AE-system that only allows storage of a limited amount of vanilla items. This way, the player can use part of the resources gathered in different dimensions, but not so much that automation in one dimension would remove the need for automation in any other.
What I'm not really sure about yet, it how the Nether and End should be regulated. Since there's no overarching progression system, they can't be staged like in SevTech and it would be nice to actually be able to use the integrations that mods provide with these dimensions. The best I can think of right now is to enable all mods, but only allow the player to take back vanilla items (possibly via the AE-system) or items belonging to the mini-pack's mods, but that might be a lot of configuration work.
For composability, these mini-packs should only contain a few mods (leaving all the general "tweaking" stuff to the base mod pack) and scripts that enable/disable most mechanics from the contained mods (like crafting recipes and mob spawning).
Apart from that they could contain some configs for world generation to craft even more specific and immersive experiences tailored to the contained mods.
I'm no expert, but it seems like it should be possible to have the player just paste the mini-pack files over the files of the full pack so the contents will be "merged". This does cause problems when there's duplicate mods or mini-packs require conflicting configs, but that's not really any less of a problem with the monolithic packs we have now. Also, there's nothing stopping anyone from creating mini-pack packs that have tested compatibility.
In addition, a single integration mod would probably have to be created that reads these configs and contains the mechanics for switching dimensions.