Eternal Orbs will literally rarer than mirrors when the Awakening hits

In fact the people running around with the customized 6th-mod will have versions that may not be able to created again. Or at least in very limited numbers. Excellent point. Now an exalt brick will not be able to be restored from an Eternal. Either the 3 rare item has to alt+regal crafted again or be bought.

I don't know what these kinds of rares are currently selling for, but since these good rares will replace the role of the Eternal Orb, they will at least cost as much as what an Eternal Path of Exile Orb used to cost.

I believe the timing of this is intentional by GGG. They are not removing Eternals after the launch, when everyone has spent their Eternals. Rather they are announcing it now, after people know of the new Maraketh weapons and associated Eternal hoarding, but before they spent the eternals.

It might be an attempt to pacify the super-rich who would be less affected, since the super-rich were already hoarding Eternals, and could even benefit from the partial monopoly they hold. The poorer population would not care much because they never saw an eternal anyway.

The only people who are affected by the chosen timing is the people trying to enter the mirror-gear crafting market. They would not have been able to hoard as much eternals, and certainly have little chance now. These people would have benefited if the Eternals were removed after the hoards were spent. But it is a resonable guess that the frustation, backlash and negative feedback from these group would be less from the super-rich.

Now even if people managed to hoard eternals, and dispite their usefulness, I don't think they will be used anymore. Holyshit, Mirror worthy gear are going to be exponenetially difficult to crafft now.