Five years? I don't think they'll wait that long.
They're working on it now, copying Toyotas and Chevys. Their first car, the Chery (yes, that is really the name) is due into the US next year.
Actually I think the number of years will be ten. A decade. Chinese cars will be making a solid foray into the American market in 5 years, but it will take them another 5 to really reach the place where the average American has no qualms about driving Chinese (plus they need to work out quality issues, just like Hyundai did in the last 5 years). Hence I'd give them 10 years.
However, once the Chinese are up and going in those 10 years, Detroit better have its ship in shape because the Chinese will be a bl@@dy tsunami. That is assuming GM and Ford are still around then in present form (i.e haven't been bought out by Toyota). Once the Chinese get into the market the entire car industry will have to go through some very serious changes (even Japan, and to a lesser extent Korea, will be affected by this ....and Detroit will definitely be killed off as we know it unless they have really taken miraculous steps by then).