I had thought about how long the publicity would hound the Oceanic 6, but in light of the proverbial 24hr news cycle, my guess is that they would have their 5 minutes. Within days or maybe a week, other stories would supplant the tale of Oceanic 6. Gawd knows that Brittany &/or Paris are always doing something that merits full-press coverage. And how likely is it that a year or two would go by, with the Oceanic 6 still so fresh in so many peoples' minds?
Although, sure, Ben & Sayid could be wintering in Berlin years into the future, I suspect otherwise. With such an imminent threat to the island, is Ben the type of murderous SOB to wait one, two, or three years before hitting back at his enemies?
On the other hand, Jack's flash forward contains some additional clues. We know that he had to have been ok at first, as shown in Hurley's flash forward. Then he had to lose his marbles. Then he had to take multiple trips across the Pacific, but only one per week. That could take us into Fall '05 & onwards.
Finally, Sayid could've begun working his hit list while Jack was still ok, and continued stalking his prey as both Jack & Hurley lost their marbles. Again, I feel that Ben will be striking quick, and striking hard.