Great points. All of them true.
I think about markets where the iPad is going to be squeezed from both the low-end and the high-end and resign it to a second-class device.
Google Chromebooks will soon run Linux apps. This is the Netbook 2.0 assault that threatens Apple in education (early comp sci, especially) and the low-end.
At the high-end you have Microsoft and its Surface. There are lots of cases where it would be nice to have direct drawing input and run traditional laptop apps. Eventually, they will get touch input to a point that’s good enough to siphon away more users.
In both cases you have devices that are better suited for typing which is critical for a lot of users. A laptop with a built-keyboard is more portable and natural and productive to me than a detachable keyboard/case that sometimes offsets the space savings and simplicity of a tablet.
I get far more productivity out of a traditional laptop than from an iPad, but I get far better free-form inputs / diagraming out of an iPad with pencil than anything else. For me, the iPad is an input accessory to my Mac and is more convenient for viewing certain content, not a laptop-replacement. I recognize there are other markets and use cases where iPad is a better-than-laptop replacement (if most of your computing revolves around websites and light text input, certain creative uses, etc.) but can see these cases being encroached upon by competition.
I’d like to see Tim Cook’s iPad workflow and setup.
A good conversation. I'd quibble with "second-class device," as it implies sub-standard. I feel it'll always have a smaller market than iPhone, but the jury is still out when it comes to iPad vs. Mac for mobile use. So, maybe "niche" is the more accurate phrase.
While there will always be threats/competition to any platform, it's usually a two-way street, and I don't expect Apple will take the current situation lying down. I visited an urgent-care clinic the other day. As I was a new patient, they directed me to one of several iPad-based kiosks to provide my medical info. There was a card holder behind the iPad to scan both my drivers license and insurance card with the back camera, and a nice, touchscreen interface for supplementary data input.
Now, if your only Mac is a portable (used as a desktop as well as for mobile), then iPad has trouble competing. However, people are finding it easier and easier to use iPad (within the Apple ecosystem) as the portable adjunct to a desk-bound Mac. I've never been a fan of using a laptop as my primary PC - I'm much happier with separate desktop and mobile devices. I haven't felt the need to have a laptop since I got my first-gen iPad. I've always carried a physical keyboard to go with that iPad, as I am a touch typist.
And as to the whole Chromebook/Surface "threat" in education and business - the ecosystem is still an important mitigating factor, as are is ease of administration, security, durability/longevity, etc. While your mention of Linux apps may have meaning for higher education, that isn't a major factor in elementary and middle schools, where iOS/Android and web-based apps are already deeply embedded.
Overall, I believe iPad is here for the long haul. Whether it's the second-largest hardware segment for Apple after iPhone, or the third behind Mac isn't all that important - it may shift back and forth over time. However, Apple is clearly selling enough of them that they're not going away anytime soon.