While we shouldn’t expect Colin Firth to reappear before Eggsy as a Force ghost in Kingsman: The Golden Circle, it’s quite possible that Harry Hart’s apparent death at the hands of Samuel L. Jackson’s Valentine has left him changed in unpredictable ways.
The spoiler-adverse Matthew Vaughn has made the point clear that Firth will be reprising the Harry role, but Firth’s character has barely spoken in any of footage released so far.
Whatever the full rationale for Harry’s survival turns out to be, there’s probably going to be a lot more to the story than “he didn’t actually die.”
The Obi-Wan Kenobi parallel that Taron Egerton mentioned to EW is particularly interesting given that the Star Wars character was also killed off in its franchise’s first big screen chapter, only to reappear in subsequent films.