And if set the comic after DS9, then you set in in the Relaunch era which is a possibility, but do are you willing to set the comic in a period that non-novel readers will find unfamiliar? If they are willing, then IDW has also to consider where it might be stepping on Pocket Book's toes and avoid doing so.
Wildstorm has already done two comic book miniseries set in the DS9 Relaunch period and featuring book characters, N-Vector and Divided We Fall.
I think that problem exists with Voyager as well. Since the crew has already made it home, and most of them scattered to the four winds, what would be the focus of the story? And, if you set it during its time in the Delta Quadrant, then you'd suffer your overall dramatic tension, since again, we all know how and when the crew finally made it back.
That's assuming that the quest for home is the exclusive focus that a VGR story can have. They told plenty of stories that weren't about that. Indeed, the developers of the show originally didn't intend the quest for home to be the overriding goal of the series; stranding the ship in the DQ was just meant to be a means to the end of telling TOS-like stories about a starship alone on the frontier with no backup and a captain having to make the big decisions with no superiors to pass the buck to. Their original intent was to downplay the search for home after a while as the crew got more caught up in exploring the wonders of the DQ. Although they didn't really try to live up to that until the third season, and then they completely abandoned it at the end of that season with "Scorpion," which pretty much locked in the quest for home as the overriding priority of the series.
So I don't think a VGR story has to be about the crew trying to get closer to home. Hell, I don't want a VGR story to be about that, since trying to run away from the frontier and retreat back to home and hearth is anathema to what Star Trek is supposed to be about. I think there's definitely room for Delta Quadrant stories, if they're strong enough as standalone tales of exploration, or if they can do something interesting with the characters within the limits of series continuity, or if they can build on the unfulfilled potential of ideas from the series (and there's certainly no shortage of unfulfilled potential in VGR).