Theories of Ynnead's Appearance Now

Could we be looking at the future of Chaos Eldar? After today's reveal on Warhammer TV, this appears quite possible that Ynnead is not really brought back, but instead is what Slaanesh has been up to?

Give us your theories...

Video by 40k Theories on Youtube
https://www.youtube.com/watch?v=mlfPhFGgOFk