Despite two fun movies, an appearance in Avengers: Infinity War, and a third film set for phase four, Marvel has canceled the Guardians of the Galaxy comic after its 150th issue. It was a fairly surprising move since the company had pushed the Guardians brand hard, including a number of solo comics for some of the group's members. Current Guardians writer Gerry Duggan isn't too bothered though, promising big stories that couldn't be contained in the group's title.
On Twitter, Duggan confirmed that the title would be wrapping up with Guardians of the Galaxy #150. Apparently, the series wasn't canceled due to low sales but because of a story that the writer pitched to Marvel. Said story is still a mystery, though it could be related to the Infinity Countdown one-shots he will be writing, one of which will star Adam Warlock. The writer did put a GIF of Warlock with the Soul Stone on his post after all.
Given the nature of comics, it wouldn't be too farfetched to assume a new Guardians comic to come out sometime after the event finishes. Marvel has relaunched a number of comics in the past, sometimes excessively to the point of indifference, so don't expect the group to go without a title for too long.
Aside from Guardians of the Galaxy, Duggan is also currently writing the ongoing Deadpool series, which hasn't been canceled and is nearing its 300th issue. Expect the writer to be involved with the upcoming Infinity event that will be teased in February. Star-Lord has been seen in the promo art, so expect a big role for the Guardians.