Modular to them might mean separate Apple-made and Apple-priced proprietary modules/components.
that could be bad.
acer is making something like that right now and from the little i've read about it, the recommendations are to stay away.
it's an awesome idea, however, pretty much the entire computer industry would have to be in on it in order for it to really work out well for the end users/customers.
modularity through something like thunderbolt or pci slots or wireless connectivity gives more options down the line than a specifically made module for a specific computer.
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edit--
well, unless the proprietary module were more-or-less just an empty container which was able to snap/connect to the larger system.. but within that module, there were a more common connector to attach parts to..
this seems pretty cool imo.. though expensive i imagine.
but with such a system, the user could build their 'box' as large or as small as they want it to be.. while giving the appearance that there are no peripheral components, just one lego'd together computer.
i personally like this idea better than making one box which everything goes inside.
i mean, with that setup (ala cMP), users either have a larger than necessary box or smaller than necessary box with very few people needing
exactly that sized box.. instead, let the outer shell grow or shrink on an as needed/wanted basis.