[Update #2]: MTG Arena's dinosaur-flavored The Lost Caverns of Ixalan is launching on November 14th.
[Update]: Alchemy: Eldraine has now arrived, and best of all, MTG Arena added the ability to favorite card styles soon after!
Quite a few months have gone by since the last Alchemy set. The reason, as you would expect, is that between the Standard-focused March of the Machine: The Aftermath supplemental set and the fully fledged The Lord of the Rings set the MTG Arena team was stretched far too thin to attempt to add yet more cards.
However, now that things have calmed down a bit, the Alchemy-focused mini expansions will be continuing as before. The first of these, the 30-card strong Alchemy: Eldraine, will be launching on October 10th with an assortment of unique cards specifically designed for Alchemy and Historic play.
The exact list of cards has not been revealed just yet, though once that happens I'll make sure to let you know. Personally, I'm hoping Alchemy: Eldraine will bring further support to popular yet currently meandering archetypes like Knights, and ideally some nerfs/bans to omnipresent cards like Orcish Bowmasters or The One Ring.
Besides the Alchemy expansion, the recent announcement has also revealed one more item of interest - a brand new Historic All-Access event, though with a slight twist. Instead of completely removing the ban list like last time, a couple of the more broken cards (*looks suggestively at Channel*) will be getting the boot in order to ensure a more interesting and competitive environment. And if this goes well, maybe we'll even get 'Few-Bans Historic' as a permanent mode somewhere down the line!
Once the Alchemy: Eldraine expansion goes live, or Wizards of the Coast announces anything major, I'll make sure to let you know. Until then, you can read a few tidbits about MTG Arena and its future over at the official website.