Upgrade path for backup storage?

So - I have a question.
I currently have two sets of backups - one at home, and one at work. Both are 2tb USB external drives. My laptop contains about 1TB of data, mostly photos and videos.
My question is about backup strategies over the long term. I expect the volume of photos and videos to continue to grow, and I have been resigned to the fact that I would have to start moving them off my laptop at some point, but so far the steady growth in drive size has allowed me to put this off. Right now I have a 1Tb drive in the optical bay and a 256gb ssd in the main bay.
My problem is that I had to restore my computer this week, and it literally took a VERY long time to restore from TM. SO - to cut to the chase, I'm looking to upgrade the speed of my mass storage -

a) I have a firewire 800 drive (not big enough), and I'm tempted to pick up some more, since I've been impressed with them. My worry is that although my 5,1 MBP will accept this, when I replace this machine I'm not sure that the next generation will have an fw800 port. Is this a doomed platform?
b) USB 3. I know my next mac will have usb 3 - it's pretty fast, and that's good enough for backups. I can get an express card adaptor for my current Mac cheaply.
c) Thunderbolt. It's very expensive, and frankly doesn't seem worth it for this use.

Advice? Thanks!