Out of all my friends, most have PCs, and out of the ones that have macs all but 1 are musicians! Musicians (pro, semi-pro, and amateur) seem to have a high ratio of Mac usage. A lot of those musicians have firewire audio interfaces. Also a lot of them use firewire HDDs too, as you can easily run out of USB ports anyway if you have a MIDI keyboard, a multi-output MIDI interface and a few other USB devices (ipod, camera, iphone, etc.).
I just blew £600ish (about $1k) on a decent pro firewire interface. This is based on the thinking that Firewire is the future for audio interfaces since I can use the same expensive interface on multiple machines (unlike PCIe where you install it in one and that's where it stays) and it doesn't have some of the interrupt issues that some USB interfaces have (most pluggable more-expensive pro-end interfaces tend to come as FW, not USB these days).
I personally am gonna get the highest spec macbook pro as it's basically a desktop replacement for me, but for many others I know they want 1 decent FW audio interface they can use with their desktop, then plug in their lower range laptop for live use. None of them will be pleased if they suddenly need a higher spec machine when replacing their macbook, and have to worry about taking a far more expensive machine on the road with them. Or buying a 2nd expensive non-FW audio interface.
Therefore I think it remains to be seen whether Apple, after years of encouraging firewire, still has them planned and we're all getting overzealous here, or if they'll be stupid/naive and screw up a lot of poor musicians on their next laptop upgrade.
There may be clever "elegant" ways of still having all the ports. Personally I don't see lots of dongles, adapters, and breakout cables as being remotely elegant though...