I understand. I don't see a problem with that scenario myself, although I also would not be surprised if Apple could keep the legacy Apple TV around as a "light" Apple TV, just for streaming at a lower price. Although the price reduction of a few months ago suggests they are probably clearing stock.
In any case the current Apple TV is powerful enough to stand a few light OS updates in the future, and considering what is currently needed to run it, I don't imagine that Apple needs to pour too much developer resource into keeping that thing current.