As i said world is in chaos and big bad seems to offer own religion and in trailer he mocks maker existence and wants peoples bow before him pretty much a big imbalance toward belief system in thedas then we have our inq that is only hope for thedas so rather i would say guy/gril have a lot possibilities here.
That the Big Bad's plan could be that is actually a sound idea. After all, it would follow the guidelines used the last time a continental organized religion was brought down. I'm talking about the Old Gods, of course.
First, it was the Magisters becoming darkspawn and their gods not answering their prayers. Then it was found out that the Archdemon was the corrupted Old God Dumat. And after his death, a new religion was born in the South condemning the Magisters and uniting a powerful barbarian invasion that weakened the Imperium's power. In the end, even Tevinter forbade their cult. The Elder One seems to be creating a worldwide crisis akin to a Blight and mocks the believers because the Maker can't answer their prayers. The Big Bad has their own cult, followers and is probably building a demonic army or something.
However, here comes the part that will make some players cringe: if that's true and that's the Big Bad's plan, it could work... but only if the Big Bad wins. And so far, it seems that the Inquisitor's goal is to stop the Elder One and their mad cult. Now add the "Herald of Andraste" title and it seems that, at the global scale, the Inquisitor will save the Chantry from the only power that could actually destroy it. Even if the actions of the Inquisitor diminish their power (compared to that from before), it would still be an acceptable loss for them.
The only way it could be bad for them is if the Chantry is somehow involved in creating the Breach. If not, it's their moral victory.