The system for the T10 gear has been confirmed a week or so back. Its a two step process, greatly simplified from the t8 and t9 method.
First you purchase the T10a using Emblems of Frost, then you upgrade this item with a special drop from the new instances. This means that causal layers can get the base t10 item, but you need the extra drop to get the best item. Basically 251 for casuals, and 264 for raiders.
I really like this. Two levels that expand on each other, and a way to get good gear for grinds, and then better gear when you get lucky, or spend your dkp.
This is the best thing I’ve heard about the new patch yet.