That said, there is expected to be some instanced content in Ashes, and if I had to bet on EITHER the Instanced or the Open World bosses being the 'Tier 5-7', I'd actually assume the Instanced ones would be.
Or that there was a ladder, where OW bosses are at Tier2, 4, 6, and are very Mitigation Check heavy, such that you need to succeed at the Tier 1, 3, 5, to have the defense gear required to stand up to them. Easy basic stagger design.
Yeah, I expect Intrepid to either go back on that design decision or to go with smth like you described. They've said that instanced bosses won't be repeatable and won't give you BiS stuff though, so I dunno tbh. There's a ton of question when it comes to their pve promises. And the "only a few % of people can clear it" is probably the most problematic one cause there's just too many implications that come with it, and none of them really work in the context of what's widely accepted as top lvl pve content in mmos.
Hm? No, their system works. Or should I say 'my system works' and I just assume it's the same?
This is a problem that is pretty common and I think the solution is known, which is another reason for my constant ragging on games like BDO. (basically, HOW did you fail this, you could literally 'read a guide for it').
Tier 1 is instanced and drops materials for armor. In Ashes, this armor would grant probably elemental or status defenses. Lots of people need armor. Very similar or exact same armor. Economy works, repairs work because lots of people run it, interesting mechanics, and since it can just be sold and isn't likely to be hoarded, it doesn't matter as much if you can't arrange to clear the T1, you can gear up experienced players with just money.
Tier 2 is Open World, usually kills anyone without Armor from Tier1. There are 8-10x as many of these bosses as there are T1 Instanced bosses. They drop materials for WEAPONS and accessories, more targeted things that help specific Archetypes or builds. Players can target them and fight over them, but because they're spread out, this doesn't have to happen as much. Eventually a guild has all the 'Zavira's Fang' or whatever they need for their Spears, and either sell them or stop farming it so they can move on to farming something to make some other weapon.
Tier 3 is back to Instanced, funneled in again, DPS and Mechanic Check heavy, you have to have T2 Weapons to clear it, or really good understanding of mechanics, otherwise you're stuck with trickle-down from whatever guilds can clear it. Drops materials for better armor/upgrades to current armor, to allow you to pass the T4 Mitigation checks. Again, you COULD just buy this off someone who can clear it, but that doesn't mean anything, your defense is better, but if you want better offense you still have to contest the T4 in Open World.
Rinse and repeat until you're out of valid Mitigation Boosts.
Result:
15-20 Instanced content across the "Odd Number Tiers".
70-80 OW content across the 'Even Number Tiers' that you can't survive being near for too long without the gear from the Odd Number Tiers.
No direct wastes of time, you can just let the Odd Number Tiers drop MORE of the material when you're strong and quickly killing them. No downside to 'flooding the market with stronger armor' once people are past the general tier. If anything it's required, the more people HAVE the T3 Armor, the more 'T3 materials' the economy needs. Crafters rejoice. OW bosses work better because they're Mitigation Checks instead of DPS checks (which obv you can just throw more people at).
I really don't expect Intrepid to have any problems implementing something at least similar.