Well, Apple would immediately have to throw their environmentally conscious PR stance out the window.
Then they’d have to spend a lot more on materials cost and machining, unless they spent even more developing more sheetforming technology than the entire aerospace industry did with an unlimited budget for the better part of a century. To do it cost effectively at all, they’d end up using some crap grade 2 “commercially pure” garbage like they make suitcases and golf clubs out of, and at that point, you might as well just stick to aluminum alloys.
Composites whip titanium’s hiney all day anyway, the same as we found in aerospace after spending all that time and your taxes. When every other computer MFG has copied them on to the gray train with a featureless monochromatic slab, and Apple is ready to differentiate again, and improve their eco-footprint, reduce costs, weight, and do some really wild thermal management, they’ll spend the money on composites, natural resins and fibers, etc. Then Apple will have come full circle, back to plastic boxes with incomprehensible bundles of miracles inside, and then they can... add a little pigment to their matrix and...