Global warming will mean that the Arctic ice will no longer completely refreeze, allowing traffic to pass through for the first time.

That is rather far fetched. Winter temperatures in the Arctic Basin average close to minus 30ºC. Water freezes very fast at that temperature.

Temperatures in Ojmjakon, Russia averaged -46C this past January.

There has been very little change in May ice extent over the last 30 years. If current linear trends continue, it will be at least 400 years before we have an ice free Arctic in May.

Conclusion : The claim that the Arctic will not completely refreeze is nonsensical.