Educational Technology is my field and this has been gaining traction for a few years now (often under the name 'Bring Your Own Device [BYOD]') and, to be honest, it is attractive to institutions because they feel it will reduce the amount of hardware that is purchased and unused (or, worse, is switched on 24/7 but doing nothing). I don't think that it is something that lecturers or students would really want if they thought about the (many) downsides.
However, the reason that laptops didn't take off is because of the patchy Wifi coverage when they were first becoming mainstream, the relatively poor battery life and few places to charge in most institutions, the weight of the devices and the startup time. With a tablet it is possible to switch it off, put it into your bag and start it up instantly in your next class - not so with a laptop.
Tablet use is obviously going to continue growing as they become more affordable lifestyle devices, but for many people they will be unlikely to replace the general-purpose abilities that you get from a full-fat PC.
That Smartboards are rubbish doesn't mean that tablets will replace them. Perhaps there is a fundamental problem with 'smartboard-style' teaching so that there will always be issues...