What would be Intel's I core equivalent to the AMD A-10 then?
They don't have a precise equivalent, by which I mean, they aren't targeting the same market. AMD A series APUs have better iGPU cores than even Intel core i's Iris, but AMD's APU CPU cores are inferior. Intel competes a little bit with lower end AMD APUs on htpcs (for streaming/recording tv) using the Atom/celeron/pentiums based on bay trail, cherry trail etc, but Intels atoms are anemic with games compared to AMD's APUs.
Some people occasionally find themselves picking between a core i3 and the best A10s, but they aren't that comparable. If you're gonna game on it and don't want a discrete gpu ever, you get the a10 easy. If you're not going to game or you want a discrete GPU immediately or even down the line, get the i3. AMD fills a gap between Intel's core i and atom line that intel itself doesn't have a product in. Intel's Core M is designed to fit between Core i and atom, but more in the cool and quiet ultrabook space, not desktops.
Intel Core i's are pricey and the people who buy them usually have enough money to buy discrete GPUs, so Iris' failings don't bother gamers and Iris gfx inclusion does let laptop makers and some business desktop makers skip adding a GPU in while still retaining good multimedia support. That's what Iris is really targeted at, while AMD APUs are really targeted at budget gaming.