As I've mentioned before Abrams is a big fan of model and yes there will be some CGI but to a lesser extent than other Sci-Fi Movies. Miniature models are still superior to cgi and the cost are almost the same. Due to the overuse of digital manipulation at the DI Stage film looks almost like digital and not vice versa (Transformers 2 is a good example). Unmanipulated film looks very different to say the RED look (Video) or Arri Alexa look (better than Video) and even a half blind monkey can spot the difference. The question is wether the moviegoers care or not.