The only way a touch display truly makes sense on a notebook is if it is a convertible.
If you can turn around the screen an slap it onto the keyboard. Basically convert the notebook into a tablet. Windows 8 is built for it Apple seems to have no intention of making it happen.
When you sit on the couch in the living room or in a lecture at the university the tablet makes sense. Checking mails, youtube, news sites, remote controlling a media center. All this stuff works great on touchpads. You can convert your notebook to one, great.
Doing Excel spreadsheets, word processing, programming, other stuff that one usually wants a notebook for than you need a notebook. If you can convert the notebook back to its notebook form great.
You need an OS that can handle both and Windows 8 will do the ground work for that. It will be a full Desktop OS with a full Tablet OS running simultaneously. The user can choose which currently works best.
One Apple guy already said in an interview a few months ago that they don't intend to go that same route. They will keep different software produkts for different hardware. Microsoft will soon have one Software that can work on all hardware and that makes more senes for them. MS can leverage Application compatibility and the one platform approach that gives users, companies the option of figuring out loads of useful options by themselves.
Apple is opposed to users figuring anything out. They will tell their users how to use stuff. They will offer a TV, Notebook, Tablet and provide everything to use it well together. MS leaves that to other companies and thus needs to offer more variability.
If that isn't obvious there will be no touch MacBook coming. I doubt there is any planned either for later releases, because Apple has no software for it and none planned. They prefer you buy multiple devices. Makes more money.