I really hope it is bolas. I would not be suprised that it is. Wizards has spent the past few sets building a team of super heros and in the same time wizards have been tying up the story of all the BBEGs. Bfz it was the lesser two titans, SoI it was Emmy. Now this block we have bolas. I am interested to see the story over these next few blocks will go. Below is my prediction.
We know The next blocks is gonna be Egyptian themed, And ajani just showed up. Elspeth is still trapped on theros which is Greek god themed. This think ajani will convince the super friends to go with him to egypt-plane to try and gain some power to save her. But the second set in the block is "hour of destruction" I think something seriously bad is gonna happen: A- bolas shows up and .poo. goes down. B- trying to get the power to save elspeth they release the planes version of apep(in Egypt mythology apep is a snake like god that is the living embodiment of chaos and destruction)