I don't think it is gonna happen,because Hornbuckle is one of Holy Men,who are priests protecting the last Dragon Egg and waiting it to hatch for Onaga to be resurrected. He is probably responsible for imprisoning Blaze to guard this Egg.

That can happen along with my idea.

Siro and Taja actually could still be alive if they did tie-in the Conquest to the actual game and I think's a great idea along with bringing in some other realms/characters: Ankha, Kiri, Queen Kreeya, Vorpax, and especially Qali. I could see Shang Tsung resurrect Queen Kreeya in the future.

Hornbuckle is a rather interesting concept and being he's already got a partial story within the game and things are fixing to alter, we may very well get the chance to play as him. Yet people do argue that his name is very odd, just like Zaggot and Abacus, I'd still like to see them all added into the story, along with the return of Tremor!!!

Anyone agree for him not only as one of Onaga's holy men but also an ally of the Great Kung Lao?

Could be alright

What powers should Hornbuckle have if he appeared in the next game?

As much as love the Mortal Kombat Konquest series and would like to incorporate it into future Mortal Kombat games, there are a couple problems with that.

1) Non-Canon: Many elements of the series does not fit the official story line of the games and at time even contradict it. If you want examples I can provide of some.

2) Mortal Kombat Konquest series is still own by Threshold Entertainment. While Midway Games went bankrupt, which allow Netherealm Studios to bought the right to the Mortal Kombat assets, Threshold Entertainment still owns Mortal Kombat Konquest along with other Mortal Kombat properties.

That said, I do want to see Hornbuckle as a character.

He should be a big dick Shadow priest, and have another name.

Hornabuckle is Chan Kang, does not is?
Is Chan Kang brother of Liu Kang, that appear in first MK movie?

Hornbuckle deserves to be in the Great Kung Lao's past.