I would think it would have the same effect on a user that it would have on a program, or the rest of that digital world, really.
It seems like Kevin's vision for the future was to allow everyone to utilize this digitization tech to go to into the computer, but as if it were an alternate reality. A perfect utopian world, in a way. You could have people living in these alternate realities exclusively, be able to fit an entire world population's worth of people into a small server farm somewhere where they're living in a utopia.
But the scary part is, like the title of the thread suggests, what happens when the computer gets turned off. Lets assume that they don't die, but lets also assume that a large percentage of people from a given region are living in one of these computer arcologies. Who is there to turn the power back on?
On a related note, the TRON 2.0 Ghost in the Machine comic covers this somewhat:
SPOILER... Mouse Over To Read:
Kevin Flynn, after the events of the first film, reflects on his experience in the computer, and, instead of feeling inspired like in the Legacy canon, becomes horrified at the idea of formatting a hard drive or even shutting down a computer. Jet suffers from the same thing in the comic.