Re: "something more durable – with upgrade paths"
well your tube argument is (unfortunately) not so relevant in this case. Tubes cost $$ and you'll need a LOT of them to do the same job as a small circuit board filled with ICs and so on. They haven't been regularly used in the consumer market since the 1980's, other than picture tubes (and they went away by 2000's). WAY too expensive (but guitar amplifiers, that's a different animal). In many cases the swapout of a tube means an expensive alignment procedure, or the thing wouldn't *quite* work properly after you swap the tube, RF and IF circuits, specifically [sometimes other things, too].
But the principle is good - swappable available components that end-users could easily repair with.
I've purchased repair parts for older stuff (replacement DVD for Wii, replacement CPU fan and DVD for Sony Vaio, new batteries and new chargers for other laptops, yotta yotta) and they're still perfectly good. Hoever, I had a bit of difficulty getting a new CD laser assembly for an old Game Cube a couple of years ago. In short I got sent the WRONG part, but the price was so low it wasn't worth returning. I had access to a 2nd game cube though, so "that" became "the solution".
[and those old game cube games work perfectly well]
admittedly, though, repairing XBox 360 has been a problem. I ended up buying 2 different "reconditioned" models to replace the first one, which broke its DVD drive. The first replacement started overheating after a year or so but the 2nd one is still working just fine. [at some point I'll go through the hell it takes to swap the DVD between the 2 older ones and get a working unit out of it].
so yeah - repair the old stuff, it's perfectly good when you do. And I really don't want to DOWNgrade to an XBox One...