Nice to hear 5tbs will be possible, but it sure has taken WD/Seagate a life time to release even a 4tb and even then its still not out.... while hitachis 4tb has been out for what a year now ?
I like the idea of a 4tb WD red drive, but fear the price.... WD/Seagate are far too late to the market with there 4tbs they will be competing directly with a £130-150 4tb hitachi drive, something tells me they will price £180-200+
Hitachi are supposed to be releasing 6tb and 7tb drives next year, they fill the drives with helium to reduce friction and heat so they can pack the platters closer together using up to 7 platters in a standard size 3.5" drive.

Won't they then make a squeaky noise when accessing data though?

a lot of these high capacity are desktop based though...portable 5tb hard drive is probably 4years away

Do you need to tether your pc to the desk like a balloon..?Hitachi are supposed to be releasing 6tb and 7tb drives next year, they fill the drives with helium to reduce friction and heat so they can pack the platters closer together using up to 7 platters in a standard size 3.5" drive.

Why don't manufacturers release a 5.25" HD.
If they do this and create a 10TB drive (say), I'm pretty sure they could increase their profit margins on these items.
The big cost to Seagate, etc, will be the initial changes to the factory which will be required to create a 5.25" platter/enclosure.
The new WD 4TB that is available now in the UK is in the £200-250 range. WD don't have a 1TB platter yet as far as I am aware, but they will need one for the 5TB. Seagate have a 1TB platter which features on some 2TB and the 3TB drive. I could see them jumping straight to 5TB. The reliability of the WD is what keeps me with them.
The WD reds are 1TB platters. Probably the only real difference with the reds that could justify them charging more.