I prefer working on my 15" MBP to any other machine. Maybe it's because I have everything installed in such a way as to compliment my workflow, but personally I think there's something extra nice about having the power of a desktop and still being able to move around from my desk at work, to trains, to coffee shops at airports and even sometimes to bed. Before my MBP, the same held true for a ThinkPad X220T, at the time running Gentoo linux.
Meanwhile my hefty gaming rigs are used for little else other than gaming. Mostly because they're running Windows which for me lacks any kind of value beyond gaming, and I haven't the time to set them up with PCI-passthrough based hvm (Via Xen or KVM or something, working with a friend on this).
Tablets? Well, I'll put it this way: The few sheets of paper that still remain in my life are not going to be escaping from their newfound home on my desk anytime soon. While I've yet to try using an iPad, neither model of Nexus 7, nor HP's surprisingly deft
Stream 7 have managed to persuade me away from my trusty laptop.
Now this may sound cliche, but there is a tablet on the Horizon that I think may persuade me to reconsider my stance - An Android powered Microsoft Surface clone, by the name of the
Jide Ultra Remix.
On top of this I know for fact that there are many developers I've either met with, or work with, who share mostly the same views. So in short, no I don't think that laptops are going to disappear anytime soon. Evolve, maybe, and I don't think that anybody even remembers what netbooks are anymore, but I don't think that they're going to disappear anytime soon.