The return of the delinquent outfit Alice! Also the next Devidol games will be so hype in like four years...
I can see the author abstaining from another Harvest Festival like arc in terms of length, probably until the manga is nearing towards it's actual end (I'd assume it ends with HS graduation and some epilogue / outro of Iruma actually becoming the Maou.) Writing an arc that spans for like 4 volumes, which is almost an entire year's worth of weekly releases is quite a feat, in terms of writing prowess probably an epic. At the same time it's taxing for the author to write a gargantuan cohesive piece. In manga, it's very, very rare that an author decides to chain arcs of such epic proportions, pun intended. It's both draining from them to write, as well as for the readers to keep up (uh, what happened like 40 chapters ago? So you know, when I knocked up the wife and the baby has been born recently, you don't really remember what happened at the start of the Harvest Festival at chapter 40~~).
I also do believe the author is growing as an artist while writing Iruma, and I do not just mean their illustrated art, which you can compare to earlier volumes and find details that have gotten more pronounced. In terms of actual drawing skills, iirc Rave Master had the biggest sudden leaps of improved art quality from what I remember (around chapter 60ish Mashima decided to git gud at drawing speedrun any%). You can pretty much see how it went from
Comiket Doujin newbie to
Well-known Doujin creator to
Reputable Magazine quality Mangaka within the span of some dozens of chapters. And now you probably only know Mashima because of Fairy Tail or Eden's Zero.
TLDR:
Those Devidol games might be closer than you think. I'll go out on a limb and say we're getting them summer 2025.
Tbf, this arc is super hype. Length-wise I expect it'll be in the ballpark of what we got for the music festival, so around 10-15 more chapters.