Everything you're saying makes sense, though I'll offer our personal experiences. We got a big LG 'smart' TV a year or so ago, and we use it for exactly four things: youtube, netflix, xbox and (primarily) to watch content I put on USB sticks. The first two are native apps. Outside of what's going on in the specific apps, there's nothing distracting happening.

So, honest question: do you think this 'TV' will be viable for at least three or four years? LG's WebOS seems to update pretty well in the background, and, as I said, it hasn't thrown up anything annoying.

So, honest question: can we expect the TV to get slower?