Since the Custodians' addition to Stellaris has been announced, any new information on the game feels as if it's not as important. However, the newest dev diary brings us interesting information on the new species and fixes to existing features.
In the most recent dev diary, and what is rumored to be the final one before a major break due to The Custodians update, developers are focusing on the issues of game balance, unity and empire sprawl, and species pack gameplay themes.
For the balance issues the game is currently facing, the developers are focusing on the Research Boom. A strategy in which power players hyper-focus research, and in doing so outpace the other empires. The main cause of this are the Shattered Rings and the Void Dwellers Origins, with the Void Dwellers not being nearly as big of a problem, though both are easy to gain access to early in the game.
The solution is to put emphasis on the fantasy of restoring the Shattered Ring with Mega-Engineering technology, and in doing so making it more of a Shattered Ring Origin story-wise, as well as making it less of an "end-game" world with its powerful Ring Districts.
Empire Sprawl and Unity is a different beast altogether when it comes to making a working solution. The current Admin Cap was not developed to its intended end, and trying to do so now seems like a dead end. Instead, the developers plan on using a different approach. Doubling won on using Unity as a resource and removing Admin Cap entirely will make the Emiper Sprawl something that can no longer be mitigated. Instead, new ways of using Unity to lessen the consequences of that sprawl will be introduced, such as Edicts.
The Species pack gameplay themes can be divided into Plantoids and Humanoids. Obvious fantasies follow Plantoids, so the developers have chosen the route of plants and growth with both adding to the Plantoids and Fungoids. The Humanoid route, as the developers say, was a tad trickier. As there are no obvious choices for the themes, classical tropes in the form of dwarves, orcs, elves, and humans are taken as inspiration.
All of these changes, and more, are subject to change, however, as nothing is yet set in stone. What remains to be seen, however, is whether with these new updates Stellaris will go the route of Star Trek, Warhammer 40k, or something in-between.