(TL;DR - Netmarble should add an AS Ch7 that lets us craft some really kick-ass cards but makes it even tougher so it's not a giveaway)

Because so many of us get stuck for so long on part of the Main Story, and because affinity kind of has no purpose once you unlock AS Ch6 for each member, I think an interesting update for AS would be a 7th "epilogue" chapter with no real story, per se, but missions that involve the members interacting with each other per their storylines that give you pieces to craft "dual" 5* cards. Example:

Tae's Orchard Boy is a stamina card, right? So 7-1 would be a mission in which Namjoon shows up at the farm chasing a lead, and you get pieces for a card that has both of them (but Tae's the main figure) and it maxes out at, say, 4500 stamina & 3500 empathy (the main stat for RM's Professional). It's the only mission that grants the pieces for that card, so you can only get 3 a day without spending gems. Maybe even make it require 120 pieces. It'll be really tough to get which is why it's so worth it on stats. Then 7-2 maybe has Tae making a delivery to the kitchen of Jin's hotel, and that card would be stamina/wisdom. And to make it extra tough (maybe even knock the stats all the way up to 5000/4000), you have to reach lvl 30 affinity to unlock AS Ch7.

Craftable cards are the only mechanism in the game other than loyalty points that allow you to kick luck in the crotch and brute-force the cards you need to clear missions, so they absolutely need to keep adding craftable cards to the game. And with the cards set up this way, it'll take MONTHS (unless you $pend the ca$h!) to collect them. The missions themselves should be easy enough to clear, about as difficult as any of the Ch6 missions, but the most important takeaway is that you have a resource now for crafting the EXACT card you need to clear a given mission. Stuck on 8-3? Grind for the J-Hope/RM card & the JK/RM card. Stuck on 8-10? Go for any combination of Jin/Jimin Suga/V. If you're really far from passing, you can even craft multiple cards with the necessary stats and use them ALL to clear it.

This way it's definitely not a quick-fix, but at least it's a light at the end of the tunnel. It's something to work towards where you KNOW, once you just put in the effort, you'll progress in the game. No luck required, just hard work and dedication.