Interesting project; I read elsewhere that the fellow announced his entry in politics the same day, so I wonder how much this is just a way to get media attention. But if it does get built, I can see it getting reasonable bookings.
The only issue is that I would think it'd be quite small by displacement compared to modern cruise ships. That's just an off the top of my head guess, so very open to correction from anyone who can be bothered to look it up. Anyway, if that guess is true, it'll be hard to turn a profit. Although I hear that the funnels will be used to provide extra entertainment space, which should cancel that problem out a bit a little.
She would not be small at all by
displacement compared to today's ships. She would be rather small by GRT though.
Titanic's displacement in normal trim, at a load draught of 34 feet 7 inches, was 52,310 tons. Her maximum permissible loading, to a draught of 36 feet, (more than she would ever be loaded to in service) produces a displacement of 55,000 tons.
Costa Concordia, to use an example of a well known modern (and also ill fated) ship, has a normal loaded displacement of 51,387 tons - slightly less than Titanic. Since displacement tonnage is "real" tonnage (ie weight), we can see that the Costa Concordia, while being physically larger, is actually slightly lighter than the Titanic.
It's really a reflection of the difference between a cruise ship and an ocean liner. Cruise ships are "fat" compared to the long, sleek ocean liners, and are built of a thinner, lighter grade of steel (they typically cruise the calm caribbean or med, and don't have to contend with the long-term battering of multiple oceanic crossings) This makes them much lighter for their size, enabling them to have shallower drafts, which allows them to visit shallower ports that ocean liners could not enter. Costa Concordia's normal draught is 26 feet 11 inches, with a maximum permissible load bringing its draught to 29 feet 6 inches.
On the flipside, the deeper draught of ocean liners makes them more stable in heavy seas. Form follows function - cruise ships and ocean liners do different jobs, and like natural selection pressure, the demands of the different jobs have made them into quite different animals.
Gross tonnage is different. A "gross register ton" is not a ton as the layman would understand a ton at all. A GRT is a unit of volume, specifically it relates to the enclosed volume of a ship. The towering office block structures of modern cruise ships, while not adding as much to the displacement of cruise ships, massively increase the enclosed volume, and so the GRT figure.
Titanic's GRT was lower than her actual displacement tonnage - a situation unheard of with today's cruise ships. Titanic's GRT was 46,329. Costa Concordia's GRT is 114,137.