Exactly. Even nowadays how many people have window seat on a widebody? some 20-25%. AVOD and external cameras can do wonders, I really like setup on Emirates.
Other problems are solvable too (aircraft is not meant to accumulate ice, you know ;) and airlines will buy anyway if fuel savings are that good in real life.
I suspect it'd still be a tough sell for aircraft manufacturers - especially for long range flights. I do 14-16 hour flights frequently and although I might not be seated next to a window knowing that they're there is sort of nice when I get up to stretch legs. Otherwise you're asking people get into basically a cave for that period of time which might be claustrophobic to even those who don't normally get claustrophobic.
Another issue might be the amount of sea sickness you might encounter given that at least having a horizon line that people can focus on helps. On the other hand... on a 14-16 hour flight if I save 50% or in the case of this like 20% to have windows versus not having windows even when not seated next to one, I might suck it up.
As a frequent traveller, I much prefer to get an aisle seat anyway.
I like the existence of the windows - which I can still sort of see on the aisles but hate sitting at the window because of the need to step over people to get to either the washrooms or the overhead compartment. It's especially important on those long overseas flights...
Other problems are solvable too (aircraft is not meant to accumulate ice, you know ;) and airlines will buy anyway if fuel savings are that good in real life.