I could picture Alice Cooper playing The Goblin King.
Metallica, Iron Maiden, Black Sabbath, and My Little Pony: Friendship Is Magic fan

I agree with the person who mentioned Jared Leto. As an actor and a singer, I can see him pulling off the role quite well.
But I think a proper sequel would be a better choice than a remake or reboot. If they went with Leto and also brought back Jennifer Connely, you'd have the Requiem for a Dream connection, and they seemed to work well together in that film. They could even have someone cast as an older Toby, perhaps searching for a way back to Jareth and the Labyrinth.
"Oh yeah, one more thing.where can I get a pizza?."

Marilyn Manson. If he lost a little weight he could do it. He can act and sing.
Lee pace would be good too. His acting as the king of the elves in the hobbit reminded me of Bowie in labyrinth a little

I just realized how ironic it is that I suggested Prince only months before he died

I doubt anyone else could pull off the costume and still look sexy. It might look silly or like a costume on anyone else. On Bowie, it looked great, like it was part of him.

How about just NOT remaking it and letting the originl classic stand on it's on?

James Marsters
Blond, the right age and build for it and the Buffy fan base is built in.
Or David Tennant.

It probably has nothing to do with the manga, honestly. The finale was pretty awful.

No I know about the manga but I didn't think this announced reboot was an adaptation of that. I thought it was a reboot of the original movie not the manga sequel.
beauty
freedom
love
truth

Clearly you missed the Return to Labyrinth manga and the Labyrinth merchandise surge at Hot Topic about five years ago where they even sold a talking Jareth doll.

Wait I'm confused so is this going to be a sequel or a reboot. Cause I don't think enough people know the movie for it to warrant a sequel especially since it came out a while ago. Wouldn't the more practical thing be to reboot/remake the movie and adapt the ending to leave the possibility of making a sequel open?
beauty
freedom
love
truth

Another choice could be Tom Hiddleston.

I really hate doing this but since you asked, Lee Pace.

A darker version with Marilyn Manson as Jareth.

The only person I've ever thought could maybe play this role other than the great David Bowie is Gackt. There's just something about him that's always struck me that way. He's the right age for the role, can write his own music, and has acting experience. I'm just not sure how good his English is.

That being said I don't think it will be a musical or have characters singing
Can you name any remake of a musical that was not a musical as well? ever?

Now this, I'm more inclined to believe:
https://twitter.com/Uncannygirl?ref_src=twsrc^google|twcamp^serp|twgr^author

Somehow, Entertainment Weekly or Variety, which references EW, just doesn't have the same ring of authenticity as CNN or BBC or the actual words of Brian Henson.
The last line in your linked article says "Sony Pictures TriStars parent company and The Jim Henson Company declined to comment." pretty much gives it away. Assuming EW did reach out to the owner companies for confirmation, the "decline to comment" would probably be because it's rather rude to talk about it right now.

That's from July. I don't know if you have kept up to speed but this past week was the announcement that they want to make the Labyrinth sequel. It was in Variety.
This is from Entertainment weekly. If you're going to correct people try to keep up.
http://www.ew.com/article/2016/01/22/labyrinth-reboot-guardians-galaxy-writer

Here is an interview with Brian Henson (it's a actually a series of videos uploaded on July 2015) regarding Labyrinth. Somewhere in this clip, he mentions that Bowie had "renewed interest" in the film as his daughter loved watching it. At around the 5:00 mark, Brian really doesn't say much about a "Labyrinth 2," so I don't think there have been any significant progress in creating one. Henson says that the company was more looking into a Dark Crystal 2.
That any remake/reboot/sequel/whatever would probably be "dark and gritty instead of ____" is the entire problem. Why not just make a different story with a different character in the same world then? Instead of agonizing who will play Jareth a la Bowie, let them first think of a story where they can still reflect the spirit of the original, yet stand on its own as a film. That's probably the more daunting task.

In my mind I always thought if they remade it, an ideal candidate to play Jareth would be Jared Leto. Firstly he's a phenomenal actor who can transform into his roles completely. He has that sort of I don't think its adrongenous per se more sort of mystical look about him he sometimes looks like something not entirely human. Plus he's the frontman for 30 seconds to Mars so if they do include musical numbers he can sing.
Reece Carney would also be a great choice he's already shown on Penny Dreadful that he can play creepy dangerous characters who have this alluring sex appeal. Plus as the OP said he can sing.
That being said I don't think it will be a musical or have characters singing at all if you look at the tones of remakes these days they tend to be "dark and gritty" with epic scores ala Hans Zimmer and a famous singer in the charts creating a song for the movie to play in the end credits that can pushed as a single.
beauty
freedom
love
truth

Allow me to repeat my bottom paragraph
No one can replace Bowie so I look for those whose sensibilities and eccentricity are equatable to him. Ones with artistic integrity and a love of Glam more than physical resemblance. Those who can capture the heart of the character. Those who are goblinesque, if you will.
They seem to be intent on making this sequel whether we like it or not so rather than shove our fingers in our ears shouting "NO ONE COULD BE BOWIE" it's best to try to pick someone who at least wouldn't be awful.

You took the words right out of my keyboard. No one else could come close. David Bowie is the only Jareth.

No one