The dead do come back to life. Zombies, vampires ghosts and Frankenstein monsters are mythical but the dead really do come back to life in the motorcycle industry.
Triumph is the succubus of motorcycling. Experiencing several near deaths since the first Triumph hit the cobblestones in 1902, Triumph motorcycles were consistently rescued from a sinking corporate ship wreck to live on while each rescuer (except the most recent) went bankrupt. Rescuscitated by Ariel, BSA, Norton Villiers, a workers cooperative who refused to go home when their factory was supposed to be closed, and a parts vendor who built a few bikes a year from left overs, Triumph staggered through the 80's and 90's while a new owner built a new factory. Today Triumph is back on track as major European builder of motorcycles, claiming to be the oldest brand in continuous production, a spurious claim given that the new bike that only inherited a name, which was probably a good thing.
Excelsiors and Hendersons were long forgotten, having built their last motorcycles in 1930, but like a ghost or the Loch Ness Monster, they re-appeared briefly in the late 1990's, in an attempt to cash in on the lucrative made in USA cruiser bike market. They ran out of cash, but not before building about 5,000 Super X cruisers before disappearing into the mist once more.
Royal Enfield "built like a gun", went under in 1970. But back in the 1950's RE spawned (licensed actually, but cut me some slack here) a factory in India. Zombie like the factory continued to build the same 1953 Bullet 350 and 500 cc motorcycles as the decades ticked past the swinging sixties, whatever the seventies were supposed to be, the 80's, 90's, no fear of Y2K digital collapse here, the immortal Bullet was the choice of Indian military, police, and the rider with a few extra bucks who wanted to rise above the horde of developing world tiddlers available to the Indian ridership. As India was still running steam locomotives and bullock carts were a common road hazard, a 1950's Bullet was no anachronism in their Indian home. The India bikes, named Enfields, presumably the Royal was unwanted given Indian independence from the British Raj, but with the rising interest in vintage motorcycles, the Royal name was bought and went on the India tank, along with the opportunity for enthusiasts worldwide to buy what every bike collector dreams of finding, a brand new, never ridden, still in the crate, vintage motorcycle. A new redesigned Bullet has lost a bit of vintage authenticity, with modernisms like EFI, disc brakes and electric starting, but like their North American doppelganger Harley Davidson, the look and feel of the ancient Bullet has been kept. Interestingly, if Triumph can claim to be the oldest marque in production by virtue of having purchased the name, they will have to step aside for Royal Enfield, who supposedly sold their first machine in 1899 and have a much stronger claim for continuous production.
The MV Agusta motorcycle were a sideline for the Italian Agusta helicopter company, mostly because owner Count Agusta, liked bikes. The most famous MVs were Grand Prix racers, the last four strokes to succeed in GP before two strokes made four strokes uncompetitive in the late 1960's (until moto GP banned two strokes). Agusta also built high quality premium priced road bikes to finance their racing team. When the count died, the company lost interest. The MV Agusta name was sold and resold to a series of owners including even Harley Davidson. The body-snatched MVs are as exotic and expensive as the originals ever were, but lacking the creds of GP racing.
The reason for all this is nostalgia. Motorcycles are more than transportation, they are fashion accessories and retro is in. In the 1970's motorcyclists mostly laughed at archaic Harley Davidson moto dinosaurs. Today Harley Davidson and their shareholders are doing the laughing. One wonders how many of the optimists who hope they can buy instant heritage by moto grave robbing will be as merry.