The reasons why NZ had plans to drop LHR before the pandemic surely still apply. While I'd love to see it happen it would be completely dependent on re-establishing itself as a niche carrier on LAX-LHR as it's clear that the economics did not stack up for AKL-LHR traffic (or, indeed, any one-stop services). The only other one-stop services operated (AKL-RAR-LAX and AKL-RAR-SYD) needed a Cook Islands government guarantee to make them viable.
However, in the spirit of discussion, perhaps those who think it's a possibility could expand more on how they think it could be made viable? Sure, crew rostering could be played with, but it's not just the cost side of the equation. They'd still have to contend with EK, QR, SQ, CX etc etc offering flights much more cheaply than NZ could.
The only way I could see NZ returning to LHR would be a nonstop service using the A350UUULR or the B787LLLR. Neither of which appear to be on the drawing board, nor are ever likely to be.
And as I said in my post they don’t anymore to an extent. Roughly 1/4 of the world’s aircraft fleet have been permanently grounded - that’s a huge drop in capacity. Many airlines are really struggling so will be slow to resume services and won’t be wanting to offer bargain basement airfares.
Previously NZ operated a base in LHR which would have costed quite a lot (despite lower pay rates for crew). Likewise, they saw the opportunity to cash in their slots for a premium. Slots at LHR are now both more available and cheaper due to Covid. So not operating another base and picking up cheaper slots would certainly make LHR service more viable. Couple that with both the UK and USA being hard hit by Covid and people in both countries wanting to come not only to New Zealand but also to visit family and friends in each other’s country. The gap in service wouldn’t be missed at all due to Covid so really it’s a route that has a lot more going for it than previously.
As for another poster about routes not resuming, EZE isn’t planned to resume any time soon (if at all), ICN is unlikely for a while either is my understanding. HKG might also take a while to resume (especially with the way it’s politics have been dominated by the CCP).