I gotta say I for one am looking forward to this case. I actually just got a rather beefy Sager laptop that can handle 2 1080s, 64GB RAM and 4 SSD/HDs (2 M.2) although I went minimalist on my rig so I can add on later. I still have two larger tower cases that in the past year I have moved completely over to M.2 SSD and SSD drives, with no spinning HDs. Thus, these two cases take up way too much room and power now. I have a separate NAS drive (5 x 4TB RAID 5) which itself is overkill for my home use, but it does allow me to not need to store lots of data that I wont use much (e.g. family photos/videos, VMs, etc) much and not require larger spinning drives in my machines. But, with USB 3.1 Gen 2, I have a 10Gbps hot swap dock for like $30 that I can use to add a spinny to my system for any purpose anyway. Which I do use from time to time. With faster networks (I only have 1GBps right now, but 10Gbps wont be far off for new homes with the advent of 4K and soon 8K video proliferating the market), the speed at copying all but probably the largest files is plenty capable so as not to need spinnys in your system anyway. Add that USB 3.1 Gen 2 flash drives are not too expensive and make it easy enough to add 128/256GB storage (although I would still opt for external or internal SSD despite being more costly).
For me, I do gaming, video editing, and software development. The first two are about the only reason to have big desktops with dual video cards, lots of storage, etc, but even I find I can work with 4K video with a single 1070 video card today and all SSD drives.. the latter of which make it much faster to work with project files anyway. I still offload via USB 3.1 or Thunderbolt 3 larger files/final renders to avoid filling up my 512GB SSD drives obviously.
Thus, what I see is that tower/atx style cases are going to fade out more rapidly with cases like this ITX coming along. The only thing the ITX MBs are missing is 4 slots of memory and the ability to run dual cards, in which case the towers/ATX will still be around for those needs. But this ITX setup with the new Asus/MSI/etc z270 ITX motherboards that support USB 3.1/Thunderbolt 3, M.2 NVMe (some do anyway), have way more than enough to do just about everything you need, including video editing and extreme gaming.
So I for one welcome the smaller design, and cant wait to replace my aging towers with the smaller form factor.