I love Cloverfeild, but I do wonder if this sequel will have problems as it was the first big monster CGI movie back in 2008 then things like Pacific Rim followed in 2013 only for Kong and Godzilla to be next all improved on the visual big monster movie medium and all brought the GCI to new levels, meaning that the original Cloverfeild movie now pales in compassion CGI wise and feels old despite still being a solid watch.
A sequel would have to do something very relevant while still staying true to source material and do new things with its CGI which it might not be able to do as it's tied to its civilian filming perspective. I feel this is really a case where they have left it far to long and it could really turn around and bite them even if they come at it from the nostalgia angle.