The cost of the earthquake is believed to be around $16 billion. The hit to the city is going to cause many people to leave. They can be expected to take their insurance payout and go to Australia. Expect about $3 billion of insurance funds plus another $1 billion in savings to go to Australia in the next 2 years. In fact some will stay here, maybe going to Auckland, if only because of the hit on the NZD will make Australian out-of-reach.
The bad news of course is that there is potentially more earthquakes to come. Escaping Christchurch might not be the solution either. The stresses being released along the Tasman Transform Fault might well shift to the North Island. Already there was a 4.5 magnitude earthquake in the Kapiti region. Of course escaping the plains and high-rise buildings offers some reprieve, so does avoiding brick (brittle) structures, or new earthquake-proof designs.
On a more positive note, Christchurch presents a fresh-faced investment to build a new city with a new image. That might take time, but it will also create new jobs, and imagine that a lot of businesses will be opening to replace those lost. Its a fresh canvas. The opportunity is also a huge risk if it lacks taste.