The costs seem to plummet far faster than even the rosiest expectations, too. A more recent auction than the Hywind project discussed by the BBC here, at Dogger Bank, has anchored turbines but is super cheap, about $50/MWh, which for the UK means cheaper than natural gas:
https://cleantechnica.com/2019/09/23/uk-offshore-wind-prices...
They recently ordered 13 MW turbines, which are absolutely massive compared to the tethered 5 MW turbines at Hywind.
Europe has been very quick at changing their offshore oil expertise into renewable energy know-how. The US is far behind, and though there are a few plans on the US Atlantic coast, it seems that our energy giants are determined to go down in the flames of fossil fuels rather than transition to the future of cheaper, cleaner energy that everybody else is building. They deserve their low market caps these days.