If they customize their hardware like they currently do and they end up selling upgrades down the line. There are two caveats I see happening and no other way. 1) they only sell CPU OR GPU upgrades (I don't count storage upgrades), 2) you must buy directly from them. It won't be off the shelf products. It'll be customized solutions.
Keep in mind this only increases development complexity.
And the tricky thing is just because you can upgrade it doesn't mean it'll be LGA format, could require soldering. For the majority of console users that's a no go. It'll have to be done by an experienced person. That's an interesting possibility.
With that said I don't see them offering upgrades. I see lots of gaming devices being offered on a more frequent basis, in regards to this roadmap.