What's the chance of a company being able to integrate perfect versions of everything onto one chip, as opposed to a number of different manufacturers each being the leaders in their fields.
I just don't see it, you'd need the very best designs and designers of everything working for one company. Your goal would have to be the very best sound, not just cost reduction through integration and some bullshit marketing claim about quality.
I'm not ruling it out, maybe chip amps will sound better than linear amps at some point, but that's far from my experience today.
Having worked for a silicon design house I'm more than aware of the limitations of the process as regards system revisions, it costs you big time to rev another chip, $100k + for dedicated silicon, as opposed to 30p to try another transistor in the discrete circuit. The odds are stacked against it..