When the coin limit is reached, future builds of the software will replace the "Generate Coins" option with a "Act as Node" or "Donate CPU" option (or similarly named). A transaction fee will be charged from then on, and any CPUs that have the option turned on will receive the payment from the fee.
On what authority do we have it that this switch is going to happen? It occurs to me that if there is some dramatic software shift, say, from "Generate Coins" to "Run Network and Collect Transaction Fees" that the network could fragment and "Transaction" coins would be rejected by "Generate" clients, and vice versa. Or, more basically, it might just...not...happen. Also, when is the switch to take place? When all 21M BC have been created, or when it becomes unreasonably difficult to create the new coins? Ie, toward the end of the 21M, it may be infeasible, in terms of electricity cost, to generate new coins alone, necessitating a hybrid of the two systems.
My main question, though - Is this a definite planned switch, or just a person's idea for what might be good to do in the future?