Yeah, this might be a one-off extreme low poll, & National could bounce back (a bit). Anything could happen on Election Day. A sudden economic "oh f**k!" event (on top of the current sh*tty economy), a 2nd wave, more scandals, etc. could easily see Labour crash down to the 40s-zone.
One thing's for certain: this is gonna get the political reporting, attack pieces, opinion section (aka attack pieces) flowing. Winston's probably gonna take it to 11 & throw everything that he can at the polling.
Its nearly August, time for any major polling turnaround is fast running out now.
It's still possible, look what happened last year here in Portugal: the PS had leads of 17-20% over the PSD in the polls in early September/late August, but by election day they were polling ahead in single digits, 7-8%.
PSD was not in a complete state of disarray having had three different leaders in the last six months before the election.