Previous promo's were by the way very strong (academy and domination). I even think blur should be nerfed a bit when it comes out.
The official stance is that promos are no more or less likely to receive errata. You should also keep in mind though that whenever they do get released, the meta may have changed. There may be a lot more answers for a promo by the time it releases, making something that currently seems overpowered much more reasonable. If a promo is truly overpowered though, it will get errata just like any other overpowered card would.