Arlovski did tear something in his knee during round 1 of his last fight. The NSAC suspended him for a couple months until his knee heals. I'm not totally sure when he's allowed back, sorry about that.
As for his return..
I'm not sure about how he could drop to LHW. I'm not saying it's impossible but he's a jacked / no fat 240. He'd have to lose a lot of muscle and I'm not sure if it'd be worth it... If he could do it and keep most of his strength I honestly think he'd clean house. Tito, Forrest, Babalu, stand NO CHANCE against Arlovski IMO. I'm by no means a Chuck hater at all, I love the way he fights, but I think Arlovski would beat him as well. I may be in the minority but I think Arlovski's strikes are cleaner and more powerful than Chucks.
If he returns to HW, I think his only competition is Sylvia still. I like Vera and think he's great, but don't think he's on AA's level yet. Kongo would get absolutely worked by Andrei. And the new Mir needs cardio out the ass to stand a chance.
"Speed plus mass equals destruction" - Brock Lesnar