What might replace a Royal Yacht?

Do we know what a modern Royal Yacht replacement would look like?

Tentative concepts called for a similarly sized, modern-engineered diplomatic ship, although many ideas were discussed rather than settled.

Tentative concepts envisaged a yacht of roughly similar size with modern engineering. Combined gas-turbine and diesel-electric propulsion could provide turbine power for high speed and diesel-electric power for most ordinary operation. A British-built gas turbine would demonstrate domestic engineering, while the diesels were expected to come from elsewhere. Other ideas included command-and-control spaces and a hangar for Royal Flight-style helicopters, perhaps two. Carrying royal cars and using a sailing-ship design were also discussed. These were competing ideas and recollections, rather than an agreed specification.