Black isn't just about being selfish and manipulative. It's also about respecting power, which is part of the reason Sarkhan as been drawn to dragons in the past.
He'll definitely still be red, but not mono-red, since he already had a mono-red card in the same block. If he's 2-colors, he's more likely to be RG than BR, but there's still a small possibility of seeing him in black. Given the ally-color theme, any other 2-color combo doesn't make much sense.
If he's 3-color (I don't think he will be), it'll be Jund colors. It works as a throwback to where he first appeared and it's been confirmed, long ago, that Dragons won't have any wedge cards. Naya and Grixis don't really make much sense since it means you'd need to play with red's enemy colors in an ally-color set.
http://markrosewater.tumblr.com/post/106159051763/so-with-ugin-in-fate-reforged-and-no-wedge-cards
sniffnoy asked: So with Ugin in Fate Reforged, and no wedge cards in Dragons of Tarkir, does that mean Ramaz won't be showing up this block?
Just because wedge cards as a group arent happening later in the block, doesnt mean there couldnt be one or two. : )