I'm still a little stunned at how many posters keep mentioning both (a) how much better of a runner she is than the other triathletes, and (b) how she has already proven she can do well in warm conditions.
As to point (a), she damn well better be the best runner among triathletes. I don't know who the second best runner is on the triathlon circuit, but I'm positive that she's nowhere near being an elite runner.
As to point (b), there is nothing like running in heat and humidity. Nothing. The only way she'll know how well she can run a marathon in warm weather is to go run a marathon in warm weather. Nothing she's done to this point is predictive at all.
It may well turn out that she's both an amazing runner and great in the heat, but nothing she's done in the triathlon is going to tell us this. She just needs to race after a full training cycle and we'll see where she ends up.
I'm most curious to see how she handles early adversity (if she encounters it). Even if she ultimately is a 2:26 marathoner, there's a good chance that her first two races could be 2:32-ish or something like that. How does she deal with that as a 34-year old mom who already has a gold medal? Does she push through, or just write the event off? Even in a best case scenario, she's not going to dominate the field like she did in the tri. How does she adapt her race strategy in light of this?