It's far from dead actually. Despite the overheads, many virtual web hosting companies are now running PHP as CGI for security considerations, because it can be used with suEXEC. suEXEC means that your scripts execute under your actual Unix user privileges, and thus are restricted by the operating system's privilege separation. This is a much more robust security model than the PHP-specific open_basedir alternative.
Also, CGI is a really simple and quite versatile interface, support for it is never going out from web servers. Many newer interfaces like FastCGI and SCGI inherit the way that CGI passes HTTP headers and other variables to the web application and back. Even PHP's SAPI mimics this with its $_SERVER variable. So CGI is not going away, it is just being built upon.
