Having a non-integrated GPU (i.e. NVIDIA or AMD) in a machine is not a stretch of the imagination these days. This means that any curious dabbler can grab Tensorflow and start learning ML. Over the past few months, I've been seeing exactly this on HN: many developers with ML Show HNs. In my opinion, it is precisely the general availability of ML that has caused this explosion.
As you pointed out, the above scenario falls away entirely under an expensive SKU. I strongly believe that having to buy any specific SKU in order to approach this stuff will spell doom for the tech. If it's not on every SKU down to the Core 2, I really can't see it taking off.
Once you have the software, a service is fine. But the ecosystem of tools around NVidia CUDA and CuDNN is there because you can buy a gaming card for a few hundred dollars and hack up libraries you find useful.