This press release has been, well, released about the Helsinki Commission Hearing where Garry Kasparov will be giving testimony on human rights in Russia next Thursday. Note it calls him "World Chess Champion," which he seems content to use among hoi polloi (certainly not in chess crowds) as a sort of honorific instead of a sporting title.
There is precedent for this. National presidents usually keep that title, for example. But that's usually for retired presidents, and players. If I wrote "this variation is often played by world champions Karpov and Kasparov" it wouldn't sound bad. Having to write "ex-" and "former" all the time is annoying, especially when you assume 99.9% of your audience know what you mean. With Kasparov in front of non-chessplayers that's not the case, however, and "former" should certainly be used. "World's #1 chessplayer" would be a politically correct way around this since he still has the top spot on the rating list.
