The 2020 rotation and the arrival of the new Standard Year will, as always, be decisive in Hearthstone.
Three expansions will rotate out of Standard mode (Witchwood, Boomsday Project and Rastakhan's Rumble) and this should create a real revolution.
While they'll still be able for playing in Wild mode, a lot of Warlock cards from the previous expansions are going to leave the Standard mode, meaning that several different archetypes that are currently shaping the meta will be affected — or will even disappear.
Some of these cards weren't really used, but the disappearance from some others will definitely be noticed...
Witchwood
Boomsday Project
Rastakhan's Rumble
Having lost just about everything in the 2019 rotation, the Warlock didn't have much left to lose. Out goes the Peer Demonist from the 2019 Hall of Fame. Only the Zoo Demonist managed to survive a little, as he has since the game began in 2013 after all. Demonist Mec'thun will inevitably leave since his trump card is departing, and only Demonist Galakrond should be left to hold the shock next to the Zoo.
After the self-flagellation and other attempts, it will be interesting to see new trends Blizzard will be looking to test for this new Standard Year.