The last fight will be between Kogarashi vs Master, but then again, we have truly never seen Nonko-san fighting seriously, so this will still be an interesting match.
We are one step closer to Yuuna Mysterious Origin. We are still having many more mysteries though, like was Tenko the previous Human Yuuna and if so then how did Yunna appear in Yuragi-sou despite the Human Yunna never step inside Yuragi-sou? There are still more questions in this manga so it will still going-on for long.
Even if Master said that Kogarashi didn't train anymore, I'm thinking that after the his 2nd fight with the Black Dragon God, he did train again off-screen. So we are in it for a Dang Awesome Last fight in the end.
And then judging from the last chapter, we are definitely in for a past/time travel arc to past to the Human Yuuna in the future.