Yeah it's a crap situation. The world never should have lost that man so early, and any choice with Black Panther will have its detractors. I myself side with recasting; letting T'Challa's story continue seems the best way for Marvel to honor Chadwick and what he gave us, in my opinion. But I can see the argument for the other side too.
In any case, the decision is out of our hands and all we can do is bitch online about it. Regardless of my personal preference, I hope that movie is good. We all need a successful Black Panther in the world.
Whatever it takes.