Yes, lots of touch devices are now being sold, but a lot of them are being sold into a channel in which nobody used a physical keyboard or mouse before (phones) and the rest are being sold into a device category that didn't quite exist before (tablets).
A lot of people seem to be misreading the decline of PC/laptop sales and the rise of tablets and smartphones as being totally interrelated when I don't believe they are. Certainly some percentage of tablets are purchases that otherwise would be have been netbooks, but IMO the bigger issue with PC/laptop sales dropping is people (granted, I'm only discussing First World people) generally already have one AND just don't need new ones as often anymore. Anything with a Core 2 Duo and 4+ gigabytes of RAM "ought to be enough for anyone" (and in my experience, for non-power-users it certainly is).
I'm a hardcore developer/gamer/"power-user" and even my system buying and major upgrade lifecycle has extended to about 3-4 years when it used to be 6 months to a year, combine that lifecycle extension with the fact that most people can get by with just a laptop (because the practical power difference between even a low-end laptop and a desktop are insignificant) and it isn't any wonder that PC/laptop sales have suffered for everyone but Apple who is one of the few smart enough to be selling systems with actual new-system differentiation ("Retina" screens).
tl; dr - I know lots of people (including myself) who have bought new smartphones and tablets over the past few years. I don't know a single one of them who doesn't use a "real" computer with mouse/keyboard daily and on average much more than their tablet/smartphone (if you exclude phone talking from the smartphone use). But their smartphones are probably like <1 year old (because significant practical hardware progress is still being made in this space) while their laptops might be years old and plenty fine for what they use them for.
If I buy an android device, then within a year there is a new one that's significantly better than the one I have in just about every way. It runs a newer version of the OS and therefor there is a much wider selection of software I can have.
OTOH my development workstation is mostly built out of scraps and I don't feel much need to upgrade it despite spending ~10 hours a day using it and I probably spend an average of 1 hour a day using the smartphone.
So spending does not necessarily correlate with usage in this case, kind of like how people may have a classic sports car that they pour money into but drive twice a month and a much cheaper daily runner that they actually use more.