That's an interesting bit of news.
Christopher Jackson and Heather Headley are exciting to hear about, although I don't expect their characters' roles to amount to all that much. That said, their song better be really good.
Actually having Askari as a character should be interesting. (And Michael Luwoye has a nice speaking/singing voice, so looking forward to hearing him here.) I was wondering if they were ever going to do something more with him given how they've started name-dropping the character a lot in recent episodes. Presumably he'll be another talking head spirit, although that does call into question how long Scar will be around - I guess they don't get rid of him by the end of this season, assuming Askari plays a role in resolving that conflict - and why Mufasa's been appearing to Kion in the first place if you could just get another ghost lion we haven't seen before who actually has experience with a functioning lion guard and thus better equipped to answer Kion's concerns throughout the series. (It never really made a lot of sense to me why a non-guard lion has been talking to Kion all this time and presumably not Kiara, who could actually use said guidance as a future monarch.)
I remember there was some concept art or storyboards someone posted here about a year ago that I assumed was going to be the Christmas episode that featured a snow leopard, so I guess this is confirmation that that story is actually happening. Very raised eyebrows on my end, given they're not African animals and they have snow monkeys in the episode as well. Is Kion going to a zoo? Is he leaving Africa entirely?