Curious though as to why Elon felt like he needed to tweet that out. Why not just wait until tomorrow? He's clearly talking about whatever they show at Battery Day not showing up in the 3 or Y until 2022. Maybe he wants to squash any speculation of 3/Y getting the battery tech but again, why not wait till tomorrow?
Because otherwise the headlines of battery day would be "Telsa admits to battery cell delay". As it is, Elon got the "bad" news out first, so battery day news can be positive.