Oh, there will definitely be complaints, and I'm going to laugh. He's already the only British-sounding lion in the series, then he's one of the few consistently white roles in the Broadway show (whereas most of that show's cast are usually black or other non-black POC; even in the South African casting he's played by a British dude). This wouldn't be too much out of step if you look at it that way, and people still love [to hate] Scar after almost 25 years.
As for the Kimba comparisons, if it's not a legality issue then I figure Disney is just confident enough that they'll at least get the money they want regardless of whether that comes up again. Heck, they're re-releasing the original film on 4K home release in December.
P.S. -- After one more search attempt, I found the source itself that originally published this:
https://thedisinsider.com/2018/03/19/ex ... ng-remake/ It's actually from back in March, so presumably they've already made their decision by now and we'll find out soon, provided Scar appears in the trailer.