Salamanders are still playable, but they are now overpriced. I certainly haven't found them mandatory. I am lucky to live in the Northwest of the US where a lot of the top players in NA happen to be. IMO Salamanders are not mandatory. Chameleons, Kroak, Skinks, and Terradons have all been able to kill what I needed removed.
An important thing to remember about the game as a whole is that the total amount of damage you need to present to cripple most armies is pretty small. Generally killing about a 1/3rd of the opponent's army is enough to outscore them. This is why mobility is such a premium stat or ability. Being able to get the units where they are more beneficial to overwhelm an objective can be all it takes to win a close game.
Honestly, Kroak is the only unit that feels mandatory to me. Bound Geminids are a close second. Either -1 to hit or -1 to attack characteristics is huge. They also pump out consistent mortal wounds. And provide a great source to finish off enemy support heroes who are hard to reach. Commet's Call, Geminids, and couple Celestial Deliverance is enough to put down the majority of non behemoth heroes. Everything else in our battletome can take it from there.