I think so too. There might be more "official" Lost product coming, but it won't be canon. Lost the series ended when The New Man in Charge epilogue was released, and although I loved Lost (even season six) I'll be perfectly happy with never watching a new Lost episode. Damon says he won't be involved, and that means anything that impacts the story (i.e. more episodes or a feature film) will not happen because he and JJ are co-creators, and JJ's a powerful man.
If, say, a video game is well done and set in a part of Lost that doesn't ruin any part of the mystery, I'm fine with it. But I don't know what that would be - Lost feels so conclusive after the ending that there's very little to actually explore, at least very little with any useful drama to it. The only thing I can think of would be the Others vs. Dharma. Say, leading up to the Truce - and ending with the Purge. Or a "Hitman"-style first-person shooter featuring Sayid Jarrah vs. Widmore Industries. Or a first-season-ish survival drama/horror featuring a young Charles and Ellie (meeting Ricardo, the bearded wonder). The last idea probably isn't a good idea without Darlton involvement, since that part still is a big mystery.