Fairy Tail Chapter 463: "Black Velvet" has been released and Natsu has decided to take manage into his own hands-and arm, specifically.
The confident Natsu has something under his sleeve, literally. Something he has created to take Zeref down.
Mangahelpers forum user 'annoyingmouse' said that removing the bandage will result in Natsu putting his life on the line to take down Zeref. He notes that in Chapter 452/6, Natsu says he can only use it once. While that does not mean he will die soon after.
However, Natsu's last words were rather ominous, as he mentioned "we've gotta say our farewells soon." The user stated that it does not sound like something the normal Natsu would say, like "I'm fired up!" or "I'll take you down."
It could mean that whatever that power is (there is a hint about the curse-it could be about Zeref's curse, but it's probably for both of them), it would take a toll on Natsu, enough to even kill him. He also expects no less from Zeref.
However, there are some who feel that it's too soon for the final battle. Natsu and Zeref were predicted to be the final face-off, unless it would take a "Naruto-Sasuke" like turn and they would face a greater foe together.
At the Fairy Tail Reddit page, user 'LateOnTheBrakes' paints a scenario similar to that, and the foe is Acnologia.
"My predictions are as follows: A couple chapters fighting. Natsu hits Zeref in the face and Zeref takes on his friendly persona. Natsu back story and him and Zeref hug it out. Aconologia crashes the party and beats Natsu and Zeref. Zeref says if you want to save your friends and defeat Aconologia you have to take this END power up."
There are still other plotlines around this fight. Brandish is still inside the Guild and everyone is distracted. The secret of his connection with Lucy still unrevealed. The rest of the Spriggan 12 are on the attack, too.