I think we'll some form of power link going from UK -> US during our lifetime, maybe via Iceland/Greenland so we can utilise the excess geothermal energy from Iceland.
There is a subsea hvdc link in the early planning stage between Iceland and the U.K. I think it is more likely the financing of the project is not arranged yet than the technology.
The cost of these links is generally cheaper than a new build power station of a similar capacity, so when you can transfer excess generation it becomes cost effective to build.
HVDC Power transmission already has links >1500km onshore. Offshore links are more expensive to build but I don’t think there are massive difference in losses (to the point where they are not worth building anyway). European countries are already connected by subsea HVDC links 500km long.
There is a planned cable between Iceland and the U.K. the costs of construction are offset against currently wasted generation, so they can be built at a comparable cost to modern renewable energy, and then they open up an energy trading market that will add to the money made through generation.