If Mordin stays with you or goes back to the ship, he'll be fine. I had Kasumi escort people back to the ship and brought Tali and Mordin with me to the final battle.
That said, I had Jacob and Jack die. Jack, I admittedly let die because she annoyed me (I let Miranda make the biotic shield and brought Grunt as the third member of the party as Jack was not loyal due to me siding with Miranda so I figured she would die. I was correct, she was devoured by the Collector bugs). Jacob on the other hand went through the vents. He described it as a suicide mission and volunteered so I said, what the hell? I was considering Tali but it was described as a suicide mission and I would much rather see Tali live for ME3 than Kaiden 2.0.
I could have loaded a file and saved everyone, but that takes the fun out of it. I want to see the effects and consequences of Jack and Jacob's death on ME3. In the future, however, I will start a new file where everyone lives and one where everyone dies but Shepard and two others (its my understanding that two crew members must live for Shepard to live).