Slight thread creep I admit, but the question of comfort & value for money was raised, rather than hammer cattle class even more.
There have been a few attempts at business class only seats airlines. They've failed. The routes are limited and the a/c needs filling.
However, there are now many travellers, of all ages, but many retired, who have spare cash and are travelling to exotic locations for luxury holidays. They want the comfort of the trip to be part of total experience. But, the difference between business & economy on these routes is huge; sometimes x4. The difference buys a whole lot of upgraded accommodation, or even 2 weeks longer holiday. OK, you can try Premium economy, the difference is worth it for the price paid, but there are limited seats. There are often no direct flights.
There are many exclusive holiday destinations where the only direct flight are charter, some with club class, or a national carrier with a stop over, or change over, costing a lot of time.
IMHO there is a niche for clever marketing between exclusive holiday companies and an airline that offers an all 'premium economy' 'club class' cabin. They would fly direct to the sunshine destinations. The holidays would be seasonal to account for monsoons, hurricanes and other weather features, and change from north to south also on a seasonal basis.
If I want to fly to Phuket, Mombasa, Grenada, Vietnam, Kho So Mui, Maldives etc. etc. to a 5* resort, I would like to fly in comfort, direct at a reasonable price. A wide body 2-3-2 with old style semi-flat reclining seats, and enough leg room to step over would be nice.
There are older B767, A330, B777 that might suit. Single type essential. You'd need 15-16 hour range to cover various departure countries, but the payload would be lighter than normal. It could be 'pan' operation based in various countries à la TUI. I'm sure there is enough money in Scandinavia, Germany, UK, Luxembourg, Switzerland, and others to develop such market.
When I flew B757 we had 213 instead of the UK norm of 238. The pax loved it, especially on the Caribbean. Price were comparable to cattle class and we were always full. Value for money as someone suggested.