If you read my posts you will find sound modelling has been around some time and with the increase in processing power is starting to increase rapidly. (Wersi get round the processing problem by using a dedicated card and not relying on the CPU to perform the calculations)
10 years from now I would be extremely surprised if sampled instruments were still around in even entry level boards. (The more expensive boards will still have better sound modelling however)
As to replacing musicians, not a chance, the musician will be able to express himself a lot more, and in a way that even the best samples cannot reproduce.

Bill