I do not think the mobile device will be a good idea to store the bitcoin block chain. It is better for the desk top.
You haven't even read the title properly, he's talking about using mobile phones to run a full node
in the future, which I think should be perfectly possible, since technological development for these devices is going at a fast and steady pace.
Plus most people have their devices powered on 24/7 and I do expect battery longevity will also improve, though that will take a bit longer than the rest (space, bandwith & processing power)