Final arc? It's certainly possible. Always better to have a plan and go out on a high, rather than fizzle and become a chore to continue following.

The way I see it, I'm an unapologetic fan of the Fairy Tail manga (cannot speak on the anime since I prefer to read), and I'd identify it as one of those series that, every time it ramped up to eleven and felt like a climactic last arc, it'd have another waiting in the wings. With that experience, it's conditioned me to never expect that we've hit the peak, and there will always be more if the audience is there for it, you know?

If Tatsu-sensei has a finite story in mind and finishes it up with this arc, he'll deserve a lot of praise for sticking to his vision. 'Cos, let's be frank: now that it has a wildly successful anime, the Dandadan property is unbelievably hot. Ending the series while it's this popular would be leaving a lot of money on the table. That'd be hard to turn down for a focused vision. If he has more story to tell, I hope he happily keeps it going (e.g. the resumption of Chainsaw Man after its first 97-chapters put a perfect bow on its story).

Plus, call me selfish romantic, but I'd like to see Momo and Okarun hook up and have a few arcs with them as a proper couple.