If the Surface was a true tablet, they wouldn't feel the need to include the keyboard in every ad. If it was a true PC, it wouldn't need a docking station - two accessories that ought to be built-in.
The "right" solution for Apple, imho, is an even lighter version of MBA - proper keyboard, Thunderbolt ports rather than docking station. Can it be hinged so that the keyboard is deactivated and stowed behind the display? Sure. Something like the articulated displays on better cameras and camcorders, perhaps.
I see little point to a tablet running OS X - the vast majority of computer users need a keyboard and mouse/trackpad. OS X already has a fair number of gestures for trackpad/Magic Mouse. While I don't think I'd use touch screen a lot (I often use a keyboard with my iPad, and I find having to reach for the screen to be a pain in that configuration), there's no reason touch can't be part of an OS X computer, so long as there's a keyboard/pointing device equivalent for every touchscreen function.
iOS devices are what they are (simplified computing appliances) in order to be attractive to the masses. There are limits to how PC-like they can become without violating their fundamental properties. PCs - general-purpose computers - have to offer greater flexibility to developers and users.
PCs certainly have to keep evolving, but for a company like Apple, the product lines also need to be distinctive - if it looks like an iPad, it'd better be an iPad.