Not sure about the analysis
I can quite easily see that for large areas of the market, SSDs will displace hard drives. The statement about how much installed capacity there is on laptops rather implies that all that space is required. That might well be so for personal users who want to keep lots of bulky multi-media files(video and, to a lesser extent, photos being the obvious ones. Also, some games are incredibly bulky. However, these requirements are far from common in the business field. In general, the storage requirments for business documents, spreadsheets and the like are far lower than for what you find in domestic usage (with a few exceptions of course). In business, the important issues are often about productivity, speed to boot, battery life, robustness, reliability and weight. Time spent in booting machines, starting programs, applying updates not to mention support staff all costs money. In the case of my company, data is synchronised with central storage, and there is considerably impetus to reduce duplication with single-instancing and keep distributed data volumes to reasonable levels. The combined system and data partition on my worktop PC is just 64GB and is only half full (albeit that there is a hidden rebuild partition).
So, to equate installed capacity with market penetration is surely not the right metric here. That the majority of installed capacity will be on HDD is surely going to be true for a long time. The same might not be the case when measured by value or installed units.
From a personal perspective, I gave up using a laptop for my photos and video storage and processing long ago. I have a laptop, but it's not got much data on it. The bulk of data is serviced centrally, where I can properly protect it. The laptop is turning into not much more than an access device and 128GB is ample, and I could probably cope with 64GB compared to the 2.5TB I have on my central storage. What I need from the laptop is that it starts fast and runs on battery for a long time. I do not want it for bulk storage. In many ways domestic households will echo business practice in this respect with centralised storage and, for heavyweight work, processing.