To start off, I won't outright call this a "leak", since I don't have much information to disclose anyways. There is very little new information that I legitimately have access to.
In addition I will not reveal any sort of personal information in order to protect myself.
Planning stages for sun/moon anime series are well underway. Satoshi is not leaving. Those concept arts that have been spread around showing the starters are in fact real and from the anime. It caused a huge commotion.
XY(Z) was written as a sort of trial for the series. Directors wanted to "test the bounds by which satoshi could grow" as well as "find a suitable role for satoshi". Meaning, they wanted to see if a more mature satoshi would resonate as much with younger viewers. As a result, Citron was made to look up to him, Shota became an important rival, and there lacked an older character in the group.
From what I hear, there was a mixed reception. In sun and Moon, ash is set to be both a mentor like figure as well as a young companion to Mao, seen in the concept arts.
His other companion? I saw it on promotional material (in development) to be the male protagonist in sun/moon. I'm guessing they will have a sort of rivalry with the gyms or challenges or what not. He had the water starter, so I assume the fire one belonged to satoshi. Maybe the plan is that he evolves it early for a change of pace? This is all subject to change though, the concept arts aren't always made to 100% match what comes out.
Also if you're curious, many people internally are interested in seeing satoshi win for once, however it seems to be in conflict with what the directors and higher ups want (from what I hear).
I apologize if you were expecting more, information is controlled tight, no matter where you are on the team or in the process