No is not so, you have actually zero chance to get them since none with a visual proof that they are droppable never ever appeared so far in this forum since this new sa was implemented (but for sure we have entire groups with tens of people and thousands of tries that never got one).

We just have right now mods that tell us that devs told them the chance is there, while themselves too never saw a single drop of them from their weekly tries, and people who claims to have gotten them once (very few to tell the truth) that is very plausible to think they mistook medium threads for advanced threads or advanced cloths for advanced threads or that simply lie just for the sake of being at the center of the attention.

What we are getting right now in sa expert mode are the same exact drops the old 2.0 hard mode used to grant, with simply the addition of the group currencies.

P.S. since 4.0 is on sight don't expect any modification of the game mechanics. Until late November we won't have advanced threads there. They'll add them with 4.0 for the simple reason 4.0 have them by default.