Close, but Nicol Bolas is trying to re-achieve 'Godhood' status. He might destroy a plane to suck it's power, but he wouldn't want to destroy the entire multiverse unless he's remaking it in the process. He's not an anarchist that wants to burn it all down, he wants total control over everything. Needs to have people worshiping his magnificence.
The 'zombies' can all have magic too. You got your foot soldier cannon fodder to overwhelm any standing armies if he needs to invade. You got your dead mages that have minor magic still. The Eternals that are super powerful zombies. Then, at the top he's got his zombie gods like the Locust/Scorpion/Scarab gods. Etc.. he has many types of soldiers now, the zombie ones are completely under his control, and then he has 'allies' like Razaketh, Tezzeret, etc.. that he's coerced into doing his bidding.
If he needs to invade or takeover something, he doesn't want to spend his own magic and do it himself. He can just send his super friends army of zombies, gods, demons, etc.. to do it and only show up himself when he really has to. Without some planar portals, though, he couldn't send them from plane to plane so easily. Now, he could even potentially go to war with Phyrexia, depending if he's figured out an immunity to the plague. This army is potentially strong enough if Phyrexia isn't absorbing them into their ranks as they fight. Pretty sure the 3 gods of devastation are stronger then anything Phyrexia has put together so far, including the 5 praetors (?). With the exception of Karn, but he got freed from them.
Honestly, I'm guessing Nicol Bolas isn't going to be defeated any time soon, and it'll take someone like Karn showing back up before the gatewatch even has a chance. I'm also guessing the story is going to be Ajani finding Karn (and others) and he joins the gatewatch after helping them 'defeat' Bolas, weakening but not killing him. In any case, I bet we don't see too much more of Bolas until the Dominaria set. Ixalan is going to be some of the gatewatch members being scolded by Ajani ('told you so!') after their defeat and splitting up to search for more allies to take him on. They said they were going to step back from all the members being in every set, they felt they over did it on that for the last two years.
In any case, the story for amonkhet has been great imo. I really dig what they've done with Bolas, and the fact he punks the Gatewatch after they thought they were so untouchable beating the eldrazi is amazing.
