MOTUnation.com

I have noticed that all of MOTUs new products over the last few years all appear to be Firewire based.

This seems to also be true of most other audio interface manufacturers.

Has the Internal (PCI/PCIe/whatever) card-based market dried up?

Oh heck no, they are doing a lot of firewire based products because the market needs that--but believe me, PCI is NOT dead. You simply can not get the I/O count over firewire you can over PCI as there just isn't the same kind of bandwidth. This is why ProToolsHD is PCI-based, the Apogee Symphony is PCI-based and of course---the MOTU PCI424 series of products that are able to handle up to 96i/o at the same time.