WHy havn't PCI devices made switch to PCI-E??

I was wondering why have PCI devices not made the switch to PCI-E slots?? That way MOBOS can just get rid of PCI slots and make all mobos now with 4 PCI-E. (right now its usally 2 PCI-E and 2 PCI if you get a good board)

Im surprised things like high end sound cards, NIC cards like the Killer NIC havnt made anything with PCI-E connections, like the X-Fi, would benefit from faster information transfers for music and such.

well, I would assume more than likely it's due to inertia. First off you have to get the big players to start making items based on the PCI-e standard, then the mobo makers to start including enough slots. For most items the added bandwidth isn't worth the price of a redesign. It's kinda like the good old floppy...for all intents and purposes it's dead, but it hangs on because it's still used.

Most of the new high end NICs are PCIe.

http://www.intel.com/network/connectivity/products/pro1000pt_desktop_adapter.htm

Most likely just supply and demand. With the prevalence of 6-channel onboard sound, demand for aftermarket sound cards has dropped dramatically, while devices such as the "killer NIC" serve only a very small niche market.

Many devices are available in pci-e: firewire and USB adapters, storage controllers and other high-bandwidth devices are now commonly available. I think what you're likely to see in the future are more USB or firewire-connected external devices like this.

what i dont understand is the PCI-E x4 slots or w.e PCI slots are actually used still but the others r like wtf