Wrong. The “popularity polls” in Russia are worthless (I speak from professional experience, from 2002 through 2006 I was the director of election polling for SurveyUSA). Kasparov would do very well in a free election where he was allowed to be on the ballot and to campaign freely and get his message out on Russian TV.
Although he was probably the greatest chessplayer ever, in the chess world he was not well-liked because he was hard-nosed and self-centered. However, his personal integrity was unquestioned, and as far as likability is concerned, compared to Putin he is a pussycat. Nobody else has the necessary combination of high profile, vigor, intelligence, flexibility, and toughness to challenge Putin.
You're dreaming, of course.
Merry Christmas.