Course, the golden city itself looked just fine at the start of Coates run too. It's the outlying areas which I think were hit harder.
Point being there's enough room for Coogler to tell whatever story he wants. The final scene does in fact make it look like everything is fine... and we can for the most part make that assumption with the world as a whole from what we saw in Spider-Man. Everyone pretty much is sweeping it all under the carpet... and it's probably fair to assume Wakanda will do. But nonetheless there is a bit of drama that the next BP film (or any film for that matter) can milk from the snap if they choose. Or they can just move on and do their own thing.
But getting back to the point of T'Challa walking off into the sunset... in large part I think that would determine if this were even an option. If Wakanda is in shambles obviously he wouldn't choose to go anywhere. But if Wakanda is perfectly fine, then it would at least be a possibility if they wanted to write the character out without killing him. Again, it's just about options...