Probably apple's next move is not to add touch to os x but to release an iOS laptop to replace the MacBook air, they could call it an iBook. It's pretty clear OS X is legacy tech and on the roadmap for being phased out.
I'd buy an iPad Pro tomorrow...if only it ran Xcode. But I can't justify $1200 or more if I doesn't help me to get my work done. At that price, and admittedly for my purposes, the iPad Pro is just a very large and very expensive gadget.
The really annoying thing is that these days a late-model iPad probably has most of the horsepower needed to pull it off.
For me it's "I'd buy an iPad Pro tomorrow...if only it ran Xcode [and had a terminal]." It can be heavily sandboxed as far as I care, I just need a proper Unix terminal. The trouble with Xcode is that it just needs so much screen real estate, I just can't see it working very well on iOS.
I assume you mean a terminal for the local machine, not an SSH session to another machine, in which case Panic's Prompt is what you want for SSH.
I'm with you in that I'd like a local terminal, but I could live without if I had Xcode on the box and some sort of full-screen editing mode. Working with storyboards would indeed suck, though.
There are terminal emulators on iOS already, that's not the issue, but not having a local filesystem means it's only useful for remoting, there's nothing a terminal will let you do on the device (unless it's jailbroken)
The MBA is already replaced, that's what the "new Macbook" is, an MBA replacement. The iBook brand was replaced by the Macbook brand and isn't going to come back (the name would collide with ibooks anyway).