you're freaking out about a game that's still 2years off. keep this up and you'll stroke out before you get your copy of Prologue.
client-server setup is not going to tax the system or the connection. It's small packets of data that is computed and sent to your screen, simple.
How many cars are on-track in Single player? oh wait, don't know that yet, as again, the game's a ways off. But suppose 16 in single player, all being processed by the unit. now instead of the unit doing the AI calculations 8 billion times a second, it's getting that data from a server, and consequently just plugs it into the on-screen entertainment that is the game.
simple.
I'm not quite sure you understand what goes on during online play... instead of computing AIs, the processing power is used to generate and extrapolate information packets into accurate data... so times 15 cars:
Current Speed
Current Direction
Current position in world (must be very accurate)
Current state of entity;
* Gas Consumption
* Tire Usage
* Emitted particles such as Smoke, sparks...
* Emitted events such as sounds, Tire squeals...
* state (damage wise even if only internal)
* Visual representation of car (especially if there is damage of some kind
Current Physical state of entity
and many others i won't bother listing here...
And that's not all, that information takes space... so lets say they can gather all this stuff in a 5kbs file; ... which must be sent every 1/4 of a second to 15 other platforms; that's 75kbs times 4, so 300kbs of information that must be sent per second... oh wait... to 15 other players... we're at roughly 4 megs. But you also have to receive that information from 15 other players, so... to be clear... you have the potential to exchange about 8000kbs (8 megs) per second... can your internet connection take it? Oh wait... I,m not even taking the time to "process" that information and display it on the screen (like you would say)... well then... that's a lot of stuff going on... naturally, a good programmers team will come up with some clever ways to send that information and pack it in smaller packages, or use some kind of encoding system and so forth... but still... its a bit more complex then saying:
"it's getting that data from a server, and consequently just plugs it into the on-screen entertainment that is the game."
Now that however, does not solve the problem of the 'ring... but generally, the bigger the stuff to load (aka "the ring"), the most processing power is diverted from processing the information packet(s). Hence my worry that the Ring might be difficult to implement for online play.