I would be more concerned about the South Canterbury farms than Rangiora ... however it sounds like that Mycoplasma bovis occurs now towards the north as well as towards the South of the location of most A2 herds.
From some reports in the radio it sounds as well the MPI is treating the whole thing with its usual incompetence (suspected herds allowed to graze up to the boundary fence with not infected herds just over the fence). If this results in additional infections I am sure this will help to improve neighbourly goodwill for years to come.
Anyway - it is a disease which is endemic in most parts of the world - i.e. people and cows can live with it. No food safety risk, either. It just means affected farms will have a higher rate of sick animals - reducing the overall herd yield.
I assume NZ farmers will learn to live with Mycoplasma bovis as everybody else does. Similar like Varroa to honey bees. Not the end of the world, just another expense and pain.