Maxi - Helli-Gurl may be "well connected", but it still doesn't alter the fact that Air NZ has been operating daily to LHR for years, not 5 times a week as stated by her, so please excuse me for having some reservations about depth of her "inside knowledge".
Debs - I'm not sure at what you're trying to get at by bringing ETOPS into the equation. Operating from the US West Coast to the UK and Europe presents no major ETOPS problems, in fact most of the flights across the North Atlantic these days are done by twin-engined aircraft. If you look back a few years Air NZ operated LAX-FRA-LAX with a 767-300 for a couple of weeks to cover some 744 heavy maintenance.
I accept that today Air NZ doesn't have the capacity to mount a twice daily operation to LHR - I did say it would be within the next 12 months which is, I believe, a realistic expectation, slots permitting.
I also made no comment about which way they were going to go to get there.
Going through the East has been looked at for years and has its advantages (especially after 9/11 and the subsequent US 'security' efforts) but equally has its disadvantages both operationally and commercially.
Going from the US West Coast has the afore mentioned '9/11' problems, however it seems that SFO is far more realistic and sensible in the way in which they carry out their 'security' obligations in comparison to LAX. It would also seem that the SFO Airport authorities are more than keen to help Air NZ expand its services from their airport.
So, as to which way - anyones' guess at this stage, but either way, it will happen.