I don't see how it would provoke a negative from whites and as a white, I think I can speak with a fair degree of confidence. It's just a bit of fun speculation. I remember a post on the BBS not long after I joined, just suggesting actors of different races for various iconic characters - to me, it's just like one of those threads like 'What if Tom Selleck was Indiana Jones or Terence Stamp was James Bond?' etc.
Some of the casting choices are odd though. Danny Trejo as Bane - but isn't Bane Latin American anyway? Or Colin Salmon as Lucius Fox - um, you've made Lucius younger, you haven't changed his race. Ben Kingsley as Alfred - not bad, but he plays varying races anyway (Indian, Iranian, Jewish, caucasian) so it's not like they've really stepped outside the box.
Suggesting Nestor Carbinelli as Batman is plain odd, because he's too old and he's already been the Mayor of Gotham in TDK (which they acknowledge) while nominating Halle Berry for Catwoman - well, enough said. Anyway, even before Halle, Eartha Kitt was a great Catwoman, so the idea of a black Catwoman is hardly earth-shattering.
I do like some of the suggestions, especially Gael Garcia Bernal for the Joker and Sendil Ramahurthy for Jonathan Crane. Alexander Siddig as Ducard - well, he doesn't have the physical presence that Liam Neeson brought to the role. Faran Tahir as Ra's Al Ghul (i.e instead of Ken Wanatabe) - not bad, but, well, given that Al Ghul is Arabic in the comic anyway, this is hardly particularly inventive. You're replacing an Irishman playing an (apparently) Frenchman who is actually Arabic (in the comic) and you're replacing a Japanese actor with an Arabic one, again to play a character who is Arabic in the comics. And of course, there has already been a black Harvey Dent, while this time the writer suggests an actor already involved in a 'change of race' controversy (Idris Elba from Thor).
All in all, I think that the writer of this article has 'cast' his names from a very limited pool. With about 4 exceptions, all of the names he's put out come from other genre movies or series - Star Trek, DS9, Heroes, Thor, Iron Man etc.
Had they suggested Vin Diesel for Bane, Don Warrington as Alfred, Jamie Foxx for Batman, that might have been more fun.