Here’s an idea, make save or die stuff not be instantaneous. The save and the death occur at the end of the player’s next turn. That gives everyone (including the player) a chance to do something before it happens. So, you are bitten by a giant spider and poisoned, but can chug a potion of anti-venom to give a bonus to the save at the end of your turn. It still happens quickly, so there is the sense of immediate danger, but it still gives a short time for help to prevent (or mitigate) it. Also, the image of a person rapidly turning to stone or feeling the poison spread through their body as everyone rushes to save them is incredibly dramatic.
In addition to the forums and “Dragon Magazine” blogs like the Legends & Lore column, WotC also has a D&D Next group where they have been posting ideas and getting feedback. Mike Mearls recently had a another piece there on save or die following up on his Legends & Lore article. There’s not much new in the Mearls piece itself, but there was this interesting comment from some guy named eberg:
There is actually some precedent for effects like save or die poison to not be instantaneous. I think this “end of next turn” interpretation is not bad, and one could even push it to the end of the encounter (i.e., make the effect take one ten minute game turn to complete). This also makes damage-based save effects (such as dragon breath or fireballs) actually more deadly in some ways, as their damage happens all at once.