One of my favourite parts of ME when playing it was Saren. His character was so deep, the tragic hero misguided into doing evil hit me hard. His biotic powers, looks and final suicide scene were the icing on the cake for him to be my favourite character. However hopes of his returning are slim, being burnt to a crisp and all but I have a some ideas as to how he can make his return.
Problem 1, his body: With the lazarus project they already had the majority of shep's body so reconstruction was (relatively) easy. Saren's body may have been mostly circuitry and burnt but samples of DNA may exist. Some government adgecies keep blood supplies of their agents in case transfusion is needed, why not Spectre's too? DNA, modern cloning and hey presto a body.
Problem 2, his mind: A clone would have no memory so would be useless without a mind, and even so Saren's was so much under Sovereign's influence could any of it be spared? I theorise that since Sovereign was able to take control of Saren through his cybernetic implants maybe when overloading a portion of Saren's mind was transferred to Sovereign's circuits. His mind and memories in a piece of Sovereign that could be uploaded to a clone body. Moreover if his mind still fights indoctrination then the code for it could be found and deleted, rendering him back to what he was.
Problem 3, his allegiance: One of the main reasons people may not want him back is because of fighting him again. But if he saw the errors of his ways he may not be a mini boss in ME3 but a DLC squad mate. The council wouldn't take him back but Shepard might give him a chance, it would certainly be interesting when hunting down the illusive man or if Shep dies in the final fight he could be the one the player takes control of for future DLC's or missions.
I admit it's stretching it a bit in terms of possibility and ME lore, but I believe it would be worth seeing Saren again. If you have any better ideas about how it could be comment bellow. If you think he should stay dead state your opinion anyway, but please don't flame to harshly.