I don't think "eliminate Dredge as a deck" is a good goal at all. You want to hurt it enough that it wins slower and/or less often, not eliminate the archetype.
I don't think re-banning Troll would eliminate the deck since it can just add Thug as a less effective replacement. I don't think a ban of Conflagrate would either. It just puts the deck all in on being able to swing through for lethal. Troll
and Imp might. Amalgam alone might. Narcomeba might. Hell, I don't know.
I'd go further and say that if anything should be banned first then it's Become Immense. Infect scares me more than Dredge at the moment, in part because you can at least somewhat hate out Dredge and it isn't as consistent at being lightning fast.
Decks like Affinity and Infect have very fast kills but they're both more interactive than Dredge currently is. There are a lot more main deck ways to
reasonably interact with Infect than there are with Dredge. Yes, Blossoming Defense made this tougher but you can still attack the deck with removal or use creatures to gum up some of their most explosive Glistener Elf hands. Most decks don't really interact with Dredge game one since you're basically hoping they whiff terribly when dredging, mulligan several times, or keep a sketch hand. Dredge match-ups currently are pretty much the epitome of one of the major complaints about the format since the match boils down to "Did you get your sideboard card/graveyard hate in your starting hand?" Even worse, the deck is so fast at getting bodies on the board that even if you have one of the hate options available in hand, a number of them can still be too slow to actually turn the tide in your favor, especially if you have to mulligan down to find it or happen to be on the draw rather than the play.
Again, as an Infect player I think Become Immense probably needs a ban unless they decide to go another route (say Elf or Inkmoth Nexus or they print a card in Aether Revolt that removes counters from players which would interact with Infect and Energy counters) but Dredge is the unhealthier of the two for the overall format as it stands.