CGI has been used for other large monsters (such as Marvel's Hulk), and this is probably a good move. In this day and age, the rubber suit looks silly, but that's not a reflection on anybody that has played him. In fact, despite Marvel wanting to recast the roles, Michael Chiklis is still a very good choice. He played the role excellently and it would be kind of cool to have him provide the voice of the CGI version.
However, Marvel is as Marvel does and they'll probably recast all four of the characters. Or possibly only three of them and a voice for Ben Grimm.