hdd tech did hit a limit, size isn't and wasn't the issue with hdd's. Most people have switched from 1-3tb main drives to 64-256GB ssd's. Speed was the limit with hdd tech, size has always improved and likely can for a very long time. 7200 rpm, rotational speeds of any kind has a limit. 99% of the improvement from hdd's to ssd's comes in random access performance where a great ssd can do 25-30mb/s random 4kb read's and a hdd has been stuck at under 1.5mb/s.
HDD's will NEVER overcome random access speeds, hybrid's merely hide it but outside of cached data can't solve it at all. That is their limit and it was pretty close a decade ago.
I had 120gb drives that can do pretty similar speeds to 2tb drives and it must be 7-8 years old at least and the very first worst SSD's blew it out of the water.
Unfortunately these days intel really is focused primarily on pushing into mobile areas, laptops/tabs/phones and really hasn't pushed hard to give us faster chips. While octo core non IGP cpu's wouldn't sell in massive volume they wouldn't cost an awful lot and there are still plenty of people who would buy it.
I still hope to god AMD doesn't stop doing them as an octo steamroller is SO much more appealing than a quad core Intel with minor speed upgrade and a IGP I won't ever use

A octo Intel chip could have been made EASILY on 22nm, probably on 32nm as well without even being much bigger seeing as you would be removing the IGP which isn't small. Die size is the real cost to Intel in terms of what they can make and still be profitable, octo core without IGP has been well inside what they can make sizewise for ages.
WIthout making them available, and getting them out there, no one will make software that can use it well. Hardware first, then software guys will use the power in time, has ALWAYS worked that way. Stupid thing is it's new hardware, pushes the software, and then that pushes your "average" user to upgrade as the software starts to run slower on older hardware. Intel stunting their performance growth is slowing the software market which is hurting their own PC sales as people wait WAY longer to upgrade. Instead of needing a bit more speed every 2-4 years, it's not 4-8 years, that is half the upgrading.