What I'm calling the (or a) SSD inflection point is the point where SSDs get big enough and cheap enough for people to switch from spinning rust to SSDs. Of course this is already happening for some people some of the time, so the real question is when it's going to happen for lots of people.

(Well, my real question is when it's going to happen for me, but that's another entry.)

I don't have any answers. I don't even have any particular guesses or opinions. What I do have is an obvious observation.

For most people and most systems, the choice of HDs versus SSDs is not about absolute performance (which clearly goes to SSDs today) or absolute space (which is still by far in the hands of HDs both in terms of price per GB and how much TB you can get in N drives). Instead, unsurprisingly, it is about getting enough space and then if possible making it go faster. People can and do make tradeoffs there based on their feelings about the relative importance of more space and more speed, including ones that make their systems more complicated (like having a small, affordable SSD for speed while offloading much of your data to a slow(er) but big HD). This makes the inflection point complicated and thus the migration from HDs to SSDs is probably going to be a drawn out affair.

We've already seen one broad inflection point happen here, in good laptops; big enough SSDs have mostly displaced HDs, even though people may not have all the space they want. I doubt many laptop users would trade back, even if they have to carefully manage disk space on their laptop SSD.

My suspicion is that the next inflection point will hit when affordable SSDs become big enough to hold all of the data a typical person puts on their computer; at that point you can give people much faster computers without them really noticing any drawbacks. But I don't have any idea how much space that is today; a TB? A couple of TB? Less than a TB for many people?

(My impression is that for many people the major space consumer on home machines is computer games. I'm probably out of touch on this.)