Yeah, I think we're bound to see more power-creep later on. In fact, I believe it already started significantly before this chapter when Tabata choose to make the fully powered Dark Triad (prior to the opening of the Tree and going 100%; still pretty much Top Tier chars by that point) be easily overpowered by the protagonists without putting any real fight whatsoever. Then, it's revealed that Lilith and Naamah stand on a different level than the Dark Triad and they're now apparently being overpowered on a 2v1 by Union Mode Asta (Devils whose individual portrayal is at least as good as Zagred's, if not better; we all know what it took to bring down Zagred).
Yeah, the remaining devils are bound to be stronger. The three rulers of the Underworld (the Devil of Time, Space and Gravity) are probably going to be on a different level judging by their hype (especially Lucifero), but that will force Tabata to grant more power-ups to the heroes since at the end of the day they'll win. Seeing all it took to bring down just Zagred, is it really feasible to take down 10 devils even stronger than him (along with the Mid, Low and possibly High-Level demons that will come out along at each level)? Not to mention, 100% Dark Triad, which are by no means fodder.
It really isn't IMO and I think Tabata is forcing himself into a corner with this whole "Tree of Qliphoth" thing. The concept is cool, really cool but realistically speaking the amount of power we're talking about is just too much for the protagonists to have a chance, even if the Devils keep coming one on one (the last level has three devils as well; probably the Three Rulers, if they come out at the same time just like Lilith and Naamah it's a slaughter).
We're probably bound to see more power-creep and/or inconsistent scaling + a lot of plot armour. Hopefully, I'm wrong here but as I said, I feel Tabata has forced himself into a corner. Either he closes the tree, making the lowest devils not fight yet and fight later on after some sort of training arc for the protagonists (because let's be real, the series is not going to end with Lucifero not making an official appearance and fighting; same with the other Devils, they've been introduced for something) or doesn't close the Tree and the Supreme Devils keep coming. I feel like if the last thing happens, it'll be extremely difficult (to not say impossible) for the protagonists to win in a way that's more or less consistent.
