Absolutely. I want to be able to walk into a store, buy some random piece of hardware and be absolutely sure that it will work under Linux. I don't care how many people use Linux, I just want to make my own personal choice to use it easier.
The question is, what market share is required to achieve this? I'm betting it's fairly low, I mean, even at 1% we are starting to see some traction. Boxes with Linux pre-installed are available from major manufacturers (albeit in a limited and hidden manner), more and more hardware makers are starting to produce drivers or release specs so the community can (I'm looking at ATI here).
If we are getting all this at 1%, then surely full-support can't need a huge amount more, I'd guess at 10% we should be good. How long it will take to get there is another question.