I loved the SQ series - in fact, I played them before I played any LucasArts adventures. Seeing a new Space Quest would be a dream come true, and I think TTG would be positioned extremely well to do it.
Of course they already have quite a few franchises whose fans they need to keep happy (cue "Where is S&M Season 3 screams"), so the question will always be whether a game will significantly expand their fanbase, because otherwise investing in a new series rather than one whose appeal is already established would be risky. However, I would think SQ would be a pretty good choice in that direction.
Re: "telltale's brand of humor": TT games already have different styles of humor in them, and it's likely that they will diversify further in this direction - perhaps even to make non-comedy adventure games (which is not to say adventure games without humor). If, say, Scott was willing to get involved with a new SQ game and the rights could be obtained, I'm sure it would be a blast, and I for one would be willing to pre-order it right now.