I think they'll keep it as resist is now, take x damage off the top (it's so easy that way!) but they'll keep the X much lower (a 2nd level spell giving 30 resist at 11th lvl? A 4th lvl spell giving 30 resist to the whole party? WAY to much resistance in 3.5!). Maybe maxing at 15 for players, 30 for creatures who were immune to it in previous editions.
I don't think they'll go with the threshold route, only because I read the red dragon entry as a sort of dispelling effect, not a threshold. It does say the breath can rip the fire resist right off of you, and sure that would fit within a threshold system (and would allow a red dragon to kill a fire elemental with its breath, which I recall from somewhere, but don't remember where), but my initial reaction was some sort of spell negation/dispelling effect rider on the breath, and I'm just sticking with my initial feeling on this one. It's not a bad idea though.
Mentat55 said:I like the dispelling or suppression idea. We had feats in 3.5E (I think in Frostburn and Sandstorm) that let you punch through resistances, so certainly there is precedent for fire so hot even fire-loving creatures get burned.
Stoat said:How do y'all think a PC's Energy Resistance v. monster attacks will interact with firey environmental hazards?
W&M tells that the City of Brass will be "uncomfortably hot" without being lethal, but one imagines that realms of deadly fire will exist in the Elemental Chaos, in the Abyss and in Hell. PC's might also find themselves in more mundane situations, such as exploring an active volcano.
Any speculation on how 4E will handle such environments?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.