As things stand, I'm pretty comfortable in saying that AST/SCH is the go to for progression content. I'm also inclined to suggest that AST/SCH is still the strongest overall combination in terms of maximising 8 man DPS as a whole.

Whilst yes, AST/AST is the gold standard for padding those rankings, you lose a significant stream of both tank and group healing from Eos meaning at least one of your healers is going to be spending considerably more time out of cleric stance.

It really depends on the content tho TBH. If we see another turn requiring very specific and substantial bursts of DPS in the same vein as A4S then yes, double AST may quickly become the norm. At this point it's hard to say really.