Due to the success of Kirby's Epic Yarn, Nintendo has gone ahead and decided to create another thread in the franchise, but from a different franchise. Yoshi's Woolly World will feature the same yarn and wool-based aesthetic as Kirby's Epic Yarn, will feature the same semi-casual and relaxed feel and tone of its predecessor, but will otherwise be entirely a Yoshi's Island game. There's no Kirby, there's no Metaknight, but there will definitely be some enemy swallowing going on.
Instead of the Kirby game mechanics Yoshi's Woolly World will be very similar to a standard Yoshi's Island game. Yoshi will be able to swallow enemies and turn them into eggs, or otherwise collect eggs from various sources. These eggs can then be used in a variety of ways to complete puzzles or defeat enemies. Mostly, Yoshi will throw them, much to the egg's chagrin.
Unlike Kirby's Epic Yarn, Yoshi's title -- while still maintaining the light-hearted nature of the series -- will ahve a much higher skill cap which fans of Yoshi's Island will expect. The speed running community won't be disappointed.