Curved glass I'd like to see come in next year, but I think iPad Air 4 is more realistic. Apple didn't bond the screen to the glass of the iPad for years after it was out on the iPhone. I think this is a process that will take some time before it will be replaceable in mass production.
I don't know how practical that would be for an iPad. I'd prefer flat glass over curved for such a large device.
I don't like curved glass and prefer chamfer edge instead. Looks more elegant to me. But I do want that unibody (or bonded glass-screen, not sure what it's called) construction that iPhone 6 has because it gives more solid feeling.