As fans now, Groot was one of the many heroes who faded from existence thanks to Thanos' Infinity Gauntlet powered finger snap. Unlike those other heroes though, not all of Groot faded from existence, as he used parts of himself to form the handle of Thor's Thanos killer weapon Stormbreaker.
In a recent interview with
He didn't say it could happen, but he also didn't say it couldn't, and Groot has spawned a new version of himself from less. The character sacrificed himself to save the other Guardians in the original Guardians of the Galaxy film, but Rocket Raccoon was able to save a piece of him and plant him in a pot.
That brought the lovable tree back to life, though as James Gunn has said it wasn't exactly the original Groot, but his son. In Guardians Vol. 2 we see Groot as Baby Groot, and by Infinity War he has grown into his teen years. If things were to reset again after this death, Groot would then spawn from the Stormbreaker handle and start off as a small plant again, and the same cycle would repeat.
As for Stormbreaker, Groot was alongside Rocket and Thor during Stormbreaker's creation. While the blade for Stormbreaker was finished, the mold fell over before the handle could be created, and to save Thor Groot uses his limbs to form the handle and unite the weapon, saving Thor in the process.
Losing any of the Marvel heroes was going to hurt, but losing Groot hurt even more, and if there's any way to get him back we can safely say that Marvel fans will take it.
Avengers: Infinity War is in theaters now. It will be followed by Ant-Man and the Wasp on July 6, 2018, Captain Marvel on March 8, 2019, the fourth Avengers movie on May 3, 2019, the sequel to Spider-Man: Homecoming on July 5, 2019, and Guardians of the Galaxy Vol. 3 in 2020.