Lets assume Cobb & Saito never made out of limbo. After 10 hours in the real world, when the flight lands (or when the sedation wears off) and they are somehow woken up - they would have effectively gone insane ..right ?

Apologies if this kind of a post was already made.

Yes. They would probably be in a coma. In Limbo they probably would've "died" before being woken up.

Time moves so slow in Limbo that they would grow old and their brains would finally go kaput.

remember that in stage three they could have been there 10 years

Didn't Cobb say that going insane was only the worst case scenario? He came back from limbo once without going insane. I think it's possible that they could have awakened after the sedation wore off ten hours after the plane took off with no I'll effects. Of course this could mean they spent any number of years in limbo as time flows differently there. All of this is assuming that the whole thing wasn't taking place in a dream.

((10*20*20*20*20)/24)/365 = over 182 years, or two and a half average lifespans. That's a long time to live alone. It would destroy him.

They would have grown old, filled with regret, and died alone.