Leinil Yu is the fifth name now attached to Marvel's mystery MU project it's been teasing this month. Again it's paired with writer Cullen Bunn, inferring a rotating team of artists - Yu, Steve McNiven, Greg Land, Adam Kubert - on some kind of project.
The most logical speculation for what MU could be comes from the common "M.U." abbreviation for the Marvel Universe. A real dark horse candidate for this would be the fictional 'lost' continent of Mu, which has been featured in Marvel Comics sparingly from the 1940s with Namora to the more recent Agents of Atlas.
Given the numerous artists and one writer, it also infers a rotating team of artists akin to the Avengers vs. X-Men and Avengers: AXIS event titles but also possibly Marvel attempting a weekly/bi-weekly type series.
The timing of the announcement Thursday at 6:45pm EST coincides with a planned presentation by Marvel at the 2016 Diamond Retailer summit in Baltimore.