Ieldra: Glad to help.

And if there's one thing I learned from technological thrillers is never say never. People in the 19th century (and I mean actual accomplished scientists, not weirdos) actually thought they had discovered all there was to discover and that science had nothing left to do. A few decads later and BAM! splitting the atom and quantum mechanics. The truth of it is we think we are good at predicing future tech but really we can't predict more than a few months maybe years at best. Sure Verne imagined a submarine in the 18th century and Da Vinci developed plans for a helicopter. But could any of them imagine a computer? And even the creators of the computer would never dream that their little programmable adding machine would one day fit in the palm of your hand (and getting smaller) and be used ubiqutously across the globe for work, play, porn and rambling discussions of ficticious catsuit- wearing characters in space.

And on that note, why wouldn't genetic engineering solve lifespan dependency on lifestyle? Of course the modifications required would be far more extensive than what Miranda currently has. But what cuts a lifespan short? Age, genetic defects, disease, and damage incurred (through physical trauma, neglect, exposure to dangerous substances etc). I'm a little rusty on my biology but aging is attributed to telomeres shortening in chromosomes right? That can be fixed. Genetic defects is a no brainer. Genetic immunity is also possible and can be achieved by studying vorcha (in real life we use sharks for similar research I think). Damage would be hardest since at this point you're talking about a healing factor a la Wolverine which must also be stable so you don't end up with Deadpool. Difficult but no reason to assume impossible.
flemm: I don't think temp LIs will make a separate appearance just to **** at you. Likely they'll work it like Shadow Broker- since you're there anyway your LI will know somehow that you've cheated and will have words with you. Simply showing up for a confrontation is stupid and petty in the face of the Reaper threat. That being said, if it does go down I hope they give Shepard the ability to put them in their place.
Jack (as an example): What the **** Shepard? You come to me with all this "make it better" crap and then you go behind my back? You're just using me like everyone else!
Shepard: You came across a battlefield, stole a ship and boarded the Normandy just to talk about relationship issues? Maybe you hadn't noticed but all life in the galaxy is about to be extinguished! Do the words "not the right time for this" mean anything to you?
Jack: Do I mean anything to you?
Shepard: I don't have time for this. None of us will mean anything to anyone if the Reapers win. So grab a gun, point it in the right direction or get the hell out of the way.
Jack: This isn't over Shepard.
Shepard: Fine. Just do you job and I'll make sure we're all still here to talk about it later.