I liked the challenge of delves.
Even though I had all complete minus potions, before potion change, we mostly complained about them. 
The problem is easing renown gives stats.
So as they are adding kingdoms and factions that will rise. They would have to rework that if they raised caps, if there was to be no reward.
So let’s say you get 36 delves at L700.
Best Delve Defeated 700 - 1400 vs 1000 points + 400
Best Delve No Casualties 700 - 700 vs 500 +200
Best Delve using Faction Team 700 vs 500 +200
800 x 36 - 28,800 that’s 7 misc stats.
That doesn’t take into account 3,300 per new faction instead of 2,500.
5 new factions - 16,500 on top of 28,800 = 11 misc stat points.
The existing hoard system would be unsustainable with the increase as it wasn’t designed that way.
Granted there are potions now, but how much more difficult would a 700 pure faction run be? That’s a 40% increase in base stats together with the 20% boost on new factions.
So realistically 700 will be 840 on new faction attempts.
That would see troops with 420 armour and 420 life doing 40% more damage vs a system that gives you +1 magic every approximate 11/12 stat rises.
At 300 hoard that’s 1.2 million gold usually. For 40 stat points it’s going to scale and be over 70 million no doubt, even with all Legendary or Mythic treasure. That’s for 1 faction, out of 41 exampled here. Granted some are easier and wouldn’t need so much gold expenditure, it’s still unrealistic for players to afford.
Let’s take the Deep King doing 40% more damage. It will hit for probably north of 200 true damage probably plus 100 splash. It’s one hit at 300 hoard.
There will need to be a rework of the system I believe. It’s not as simple as simply increasing the level. The gap and cost becomes prohibitive, and stat bonuses could give power creep easier then Devs intend at this stage.
They could cap as is to offset stat gains but the system would need more time than Devs invest I think.