Everyone's favorite patter-singing Salarian Scientist can be saved...
But the price, and required setup is arguably too high:
In order to keep Mordin alive, you need to have 1) Not saved Maelon's data in ME2, and 2) Urdnot Wreav must be the leader of the Krogans (that is, Wrex must have died on Virmire in ME1).
Incidentally, this is the default state for a new, non-imported Shepard. Under those circumstances, and only under those circumstances,
Mordin can instead be persuaded to lie to the Krogans about the Genophage cure, and they will buy it, hook, line, and sinker. At this point, you gain both the Krogans and Mordin as War Assets.