Stepping back from the game as producer makes sense. There's a bit of speculation here but observation is this:
From what I remember there were some health issues with Mesanna in the past; I think it was like 2 years ago at this point where NL was pushed out due to "a member of the team missing time" which ended up being Mesanna. So there might be some health things there OR maybe those previous health issues gave her the view point to enjoy her time doing things she actually enjoys doing.
This is not meant to be fresh insult directed at Mesanna, but I've been questioning (along with many others) for the past several years what she's actually been doing. To me the writing was on the wall that she was just riding it out for as long as possible doing what she wanted / how she wanted / when she wanted and very possibly had very little oversight. Personally, I felt there was a sharp drop-off in content/communication when COVID hit which was understandable at first but didn't really improve until recently; it had all the signs of someone not focused on their job (for whatever the reason). We reached a point where the "monthly newsletters" were coming out twice a year and had very little information of what was going on. The level of interaction just wasn't there.
Being the lead of GM/EMs makes sense for her. She's still involved in the game but is in a position that probably doesn't really need a ton of oversight and won't have as many eyes judging the end product.
About the new producer... There have been several interactions with Kyronix does seem to think grindy things are good but he also seems to usually be more open to feedback compared to (presumably) his predecessor where it (seemed) was her way or the highway. Recent examples probably stand out best where the MoE was being killed too fast on ATL and shadow hounds were being wiped out so there was a hot fix put out for it that was beneficial for everyone (TMappers got auto credit / Damage based on ppl there / shadow hounds spawn with t chests). Additionally they added the Solen Hives for the ToT because the bots/lag was too much to handle in the towns which was successful, for me at least, in allowing people to collect drops with less headache. To me this shows that someone is listening and changing things as needed.
Another thing is that we've had the first actual published roadmap in 5+ years. I think this is great! The feeling of accountability has returned because there are actual ideas being put out there with dates, instead of something like "NL will be released soon".
Overall, I am looking forward to Kyronix being the producer and hope that he can help keep cranking out new content while keeping the lines of communication open. If that can be done, I will gladly keep paying my subscriptions and have no problem supporting him as the new producer.