Major Apple TV updates have been years apart, and they've never rushed to have the highest resolution for TV content. I'd say it would at least be a surprise if they announced some kind of 4K unit this year.
If you'd really stress about 4K, you could wait to see whether there's a March event and then find a sale for a current-gen model afterwards if nothing was forthcoming.
If you'd really stress about 4K, you could wait to see whether there's a March event and then find a sale for a current-gen model afterwards if nothing was forthcoming.