We are now in a strange place for the Dredge deck, though. As a mechanic, it will be in Extended for a while, but as a deck it has undergone some fundamental changes, as many of the enablers that made the deck work have disappeared. There is no Putrid Imp or Breakthrough to get the cards you need into your graveyard, and no Cabal Therapy to clear the way or serve as a clutch discard outlet.
What does this mean for Dredge? Well, it definitely lost more than it gained with the Extended rotation, but from a metagame standpoint, it might actually be better positioned than before. Nikolaus Eigner and Phillip Summereder of Austria are both showing that Dredge can still work, and are presumably enjoying the fact that this might be the most "Dredge-friendly" metagame that has existed since the deck came to power. Each remains well in contention for Top 8 at the time of writing.
So how does the new version of Dredge reconcile what it has lost? The answer is to get in new draw and discard effects so that the endgame can remain similar. The deck isn't quite as fast now, but is still plenty quick enough to cause worries for most decks in the format. The discard outlets of choice now are Ideas Unbound, Goblin Lore, and Magus of the Bazaar. And while Dredge has lost much of the flashback mechanic, it has gained access to unearth, and in particular Fatestitcher. Fatestitcher serves a number of roles in the deck. On occasion it will be a clutch "extra guy" to get Dread Return going. Sometimes it will get unearthed to tap down a key blocker so that the math works out for attacks with something like Akroma, Angel of Wrath. Most excitingly, though, Fatestitcher plays very nice with Magus of the Bazaar, to the point that one turn with a "live" Magus is probably enough to go from zero to hero, as Fatestitchers chain into each other.
Interestingly, there is another deck that functions similarly to Dredge in its endgame, but which would probably not be fair to call Dredge due to a key difference: it doesn't actually dredge things. With Mesmeric Orb, it can engineer a situation where a pair of Fatestitchers commence untapping each other in turn, to mill itself enough for a "classic" Dredge kill. Given that Fatestitcher works so well in regular Dredge, it feels like there might be a merge in the offing among the graveyard combo decks.
Dust off those copies of Leyline of the Void. It turns out that Dredge wasn't dead—it was just playing in the graveyard, as usual.