You don't have to upgrade. Don't upgrade... but if you do, there are adapters for you that will allow you to continue using your old gear.
And I'm not an outlier case. There are a lot of audio professionals and semi-pros that depend on old Firewire interfaces. These were Apple's market for selling high-end laptops! This is basically just disregard for your oldest and frankly most profitable customers. If I didn't feel like a new MBP would actually be sacrificing functionality, I'd probably have upgraded already. Instead, I'm considering a platform switch. That's bad.
btw, as someone who didn't use firewire, i hated that port. waste of space, could have used an extra usb port instead. and it wasn't like there was a lot of gear that used it, unlike e.g. ethernet or vga which sometimes came in handy (i also loath vga).
USB2 was more competitive, but Firewire stuck around due to its lower latency for audio applications.
And actually you aren't Apple's most profitable customer since you are still clamouring for old technologies. It's early adopters that upgrade every year that are the most valuable to Apple.