My guesses for the next MBP:
Quad-Core Mobile processor
8GB RAM (2x4GB - the current CPUs already support 8 gigs, but no one makes 4gb sodimms yet)
500gb Samsung M6 9.5mm hard drive option; 320gb 7200rpm option
HDMI or DisplayPort
eSATA
LED backlight standard on all models
Bluray option
I don't really know what the deal with Wimax is. Apple pretty much stays with standards-compliant stuff, which I think is why Blu-ray hasn't been released on any models yet (since the format war was previously undecided). Wifi B, G, and N are pretty standard, but I really haven't seen too much done with Wimax. Unless AT&T is planning some huge roll-out and the iPhone rev2 has Wimax built-in, I don't think we'll be seeing it in laptops either - simply because the infrastructure isn't there yet.
I'm not 100% sure on the Quad-Core Mobile chips yet because from what I've read they're meant for high-end gaming/workstation-replacement laptops, probably like Sager would sell. i.e. they're power hungry. Apple isn't going to release a laptop that only gets an hour of battery life, so we may be stuck with dual-core mobile chips for awhile. I really, really want to see an 8gb kit available for laptops; Santa Rosa chips have supported 8 gigs since their release, but no one makes 4 gig memory chips!
MCEtech offers a 1TB, dual-500gb kit for the 17" MacBook Pro; 12.5mm 500gb drives are already available and 9.5mm drives (the Samsung M6) is due out at any time, so that's definitely a valid option, especially since there's no 400gb laptop drive available for Apple to put in there. FastMac offers Blu-ray burners for MacBook Pros already (albeit at $999 a pop), so that's a good future upgrade option once the prices go down. But, Apple would have to put in an HD BR player into their operating system and probably update iLife and Final Cut Studio and whatnot to support it natively. I think that Apple has been tight-lipped about whether their products are HDCP complaint or not, so who knows what the future holds there.
Mostly I just want a 12" MBP