Milotic is likely not getting any mega-evolution, but I believe Flygon is still a possibility, which is great! I've been waiting for its mega-form for a decent amount of time, and it'd be nice to see that finally happen.
It is highly unlikely to happen that Milotic will get Mega Evolution but in the end it's still reasonable considering it is Gyarados' counter part and one of the main characters use it as his main. Though Wallace won't be Champion in these games there's always that small chance it'll happen. But in the end I'm either way more than happy if at least Flygon gets Mega Evolution. Maybe Milotic will get it in next generation's games, who knows. :D Plus in the end Flygon would really need that Mega more than Milotic so it could shine out finally. Ah, just love Flygon <3