The damage from the Kaikoura earthquake is significant, and current estimates are that it will take a year or more to repair road damage and enable state highway 1 to reopen. In the interim the inland route is open but it adds a couple of hours to the trip from Picton to Christchurch.
We had planned on stopping for the night on our way down the east coast of the south island at Hanmer Springs. Looks like this will be most convenient now considering the extra driving time that will be incurred. Apart from that it looks like there wont be too many other interruptions. Unless there is a big aftershock that causes more damage.