The last cross-channel commercial hovercraft was in 2000, killed by its gas guzzling, the Channel tunnel, and the more efficient and reliable catamaran ferries which replaced them. They were fun and fast, though - 60 mph across the sea, Dover-Calais in 25 minutes, but massively bumpy as they chopped through the swell instead of riding it - like driving fast over cobbles. In the days before the chunnel and low cost airlines, I did the quick and cheap way several times from London to Paris, which was to take a Dover-Boulogne hoverflight with train connections at each end. Still, it took 5 hours end to end which cannot compare with 2 hours on the high speed train today.
You can still get a hovercraft from Portsmouth to the Isle of Wight.
The French hoverports were fun - the beasts would come in over the beach in a flurry of sand. The landing pad of the abandoned hoverport at Boulogne is still clearly visible from the air.

Pessimism is the soft option.