If Davy Jones died in the 3rd movie of POTC At World's End, before Cutler Beckett died, does the Locker itself still exist even though the creator of the Locker died? If the Flying Dutchman has a new captain, does he control the Locker?
I think the Locker is sealed forever until a new captain of the Flying Dutchman is found. At least that's what I think it is. In the story, his original purpose was to carry souls of those who died
at sea from this world to the next on his vessel. He was charged with
this noble and just duty by his one true love, the sea goddess Calypso.
For every ten years at sea he could spend one day on land to be with
her. Ten years after first being charged with the duty, Jones prepared
to be reunited with his true love, but was heartbroken and enraged when
she did not appear. Unable to deal with the sadness of Calypso's
betrayal, Jones, through some unknown supernatural means, ripped out his
heart and locked it in a chest, burying it on the plague island Isla Cruces.
This chest became known as the "Dead Man's Chest", thus becoming the
primary object being sought after in the second film. Jones then
abandoned his past duties, and instead returned to rule the seas as a tyrant with a damned crew bound by oath to serve aboard the Dutchman for one
hundred years each. Because Jones and his crew broke their oath on the
Dutchman to ferry lost souls, a curse slowly transformed them into sea
monsters as their physical appearances matched the darkness inside of
Davy Jones Early Life
Davy Jones was born in Scotland;
nothing is known about his youth. He fell madly in love with Calypso,
the "heathen god[dess]" of the sea who gave him the charge of ferrying souls who died at sea to the "other side," Fiddler's Green. Calypso gave Davy Jones the Flying Dutchman to accomplish this task. Her reason for this is unknown. She swore that
after ten years she would meet him and they would spend one day
together before he returned to his duties. He faithfully kept to his
charge for ten years, and after his first decade of duty, prepared to
see his love again. Calypso, however, after those ten years, failed to
show up because of her capricious nature, which had drawn Jones to her
in the first place. Believing Calypso had betrayed and abandoned him, a heartbroken and enraged Davy Jones turned the Pirate Brethren against her, saying that if she were removed from the world, they would be able to claim the seas for themselves. They assembled in the First Brethren Court and Jones taught them how to imprison her into her human form (Tia Dalma); the Court agreed with him to imprison her forever.
Soon, Jones' grief at Calypso's betrayal and guilt at what he had
done became so great that he carved out his heart, and placed it in the
"Dead Man's Chest". Containing a powerful lock, the Chest was sealed and
placed within a larger wooden chest along with Jones' numerous love
letters to Calypso and all other items having to do with her, except his
matching musical locket. This was then buried on Isla Cruces,
a plague island. Jones then departed, keeping his unique double-stemmed
key to the Chest with him at all times. Since then, Jones has abandoned
his duty and sailed the seas, making deals and doing as he pleased.
Though immortal, his disregard for his duty brought punishment, mutating
him into a parody of humanity, and with him, his ship, and whomsoever
served on it. His crew is lured into service by the notion that they can
forestall their "final judgment" for 100 years by serving aboard the
Dutchman, however, they don't know that they will slowly mutate into
creatures like Jones until they are essentially barnacles on the ship's hull, ultimately useless. The lore of the "feared Flying Dutchman"
begins as Jones' eerie ship sailed about destroying ships to recruit
for crew. With his supernatural power, he becomes ruler of the oceans'
realm and comes to command the Kraken, a feared mythological sea monster.
In the book series about Jack Sparrow's
earlier adventures, Davy Jones shows interest in the Sword of Cortes,
also sought by Jack. He is a minor character, but finally appears in the
cliff-hanger ending to book 7 as Jack and his crew encounter the Flying Dutchman.
identify the traitor among them, who turns out to be Borya Palachnik,
the Pirate Lord of the Caspian Sea. After Cutler Beckett sank Jack Sparrow's ship, the Wicked Wench, Davy Jones approaches Sparrow with a deal: Jones will raise the Wench back from Davy Jones' Locker, allowing Sparrow to be captain for 13 years if Sparrow agrees to serve on the Dutchman for 100 years.
I know this is super long and with too much detail, but that is all I can give you.