Thanks for your comment, and question.
My comments above were targeted specifically for the audience with whom I was speaking: mainly telecom ministers in middle and low income countries, many of whose countries are considering, if not already pursuing, large scale investments in ICT use in the education sector that in many cases seem to be disconnected from what is happening with technology use in broader society. While I don't work in environments where your organization works (which you quickly describe in your comment), I would expect that my comments above may not be quite as relevant, for a number of reasons.
For example: While I don't haven't looked at the survey data for the UK recently, I know that in many other industrialized countries, many low income students access the Internet (whether this is through their web browser or some other app) predominantly using their phones when not in school. Even if they can afford this use (and this is a VERY BIG IF in many cases), they are in effect competing with students from more economically privileged environments who have access to phones -- AND to computers (and tablets and game consoles and ...), AND to broadband, at home and in their communities. 'Mobile first' in such contexts carries with it very serious ramifications related to equity that perhaps are not as immediately acute as in most of the places where I work, where the installed ICT infrastructure is much lower across the board.
That said, I guess a quick point that I might make relevant to the scenario that you describe (or one of my points) would be that this reality be acknowledged, and strategies to reach out to, engage and support students in such contexts be cognizant of the increasing dominance of mobile technologies among certain key groups of students and communities. At a basic level, this means that, if there is a de facto assumption that students need to access the Internet to be able to do their homework, that you make sure that official context made available by the education system is fully accessible on mobile devices. (This is often not the case, in my experience.)
This is only one small piece of a much larger puzzle, of course -- doing this does not obviate the need to provide (more, better, cheaper) access to broadband and other types of devices (including 'traditional desktop PCs with large screens and keyboards, laptops, tablets, etc.).
But again, this isn't my particular area of focus. As noted on the upper right corner of the screen on the EduTech blog (at least as appears on the 'desktop' version of your site -- it may or may not appear there if you are reading this on your phone!), the aim of this particular blog is to 'explore issues related to the use of information and communication technologies to benefit education in developing countries'. With this in mind, I expect many other folks would have more complete, more targeted, and more articulate answers to your question.
Thanks again for your comment.