Agreed, it all depends on if the home menu can support it.
That being said, the Switch as a portable should be accessorizeable. The main unit may or may not be available with different skins - like the 3DS - But I genuinely expect that the Joy-cons can be swapped out for all sorts of funky styles and colors (maybe a GameCube style one?) and themes should be a probability.
But if the main unit will come in different colors, then I'm totally going to switch to a Gold Hyrule Edition Switch when it comes out.