TBH, if they are serious about re-releasing the Calibra name then they really should keep the shell as close to the original as they can (light clusters in line with modern cars though). The interior can certainly be updated, the chassis completely different & a good range of engine options.
Astra's, Vectra's, Corsa's etc have always had facelifts but with no stop in production so we tend to get used to each design & still assosiate the name with it. Releasing a coupe that bears absolutely no resemblance to the model that ceased production 14 years ago & whacking a Calibra badge on the back is utterly pointless IMO.
It may not turn out to be a bad looking car but it certainly doesn't deserve the Calibra badge.