I figured combining would work best. Michael may have one more fight left in him if it involves defending his home. Sanya has been holding down the fort for a while now and will continue to do so. I see Butters giving up the sword after the BAT unless something happens to Andi and then he will keep fighting. Another will rise to join their ranks. My best guess is Daniel.
Personally, I'm betting on Amanda Carpenter. My dad (who I finally got to start reading again thanks to the fun factor of the Dresden Files a few years back) brought it up to me as a possibility, and I think I like it. Daniel's priorities aren't what they need to be to be a good Knight, at least not yet. He's too hotheaded—he's his mom, not his dad, if that makes sense. And the one member of the Carpenter family who's always seen being as patient and caring as Michael is Amanda. (And Hope's observation about Daniel being the Boss Kid, but yelling a lot more kind of speaks volumes about his character). Daniel just strikes me as someone who doesn't understand the Swords; we see him asking for them, but I've always thought they were something you needed to be offered.
I think Sanya is going to die. He'll be laughing when he goes, because he's a Mad Russian, but he'll go.
Butters is tricky. If I'm writing it, he lives, and stays on until a new Knight shows up.