But at the moment the edo jinchurikis are in limited treasures. So it's up to Tencent if they to have a new treasure with edo jinchurikis as rares or continue to have edo jichurikis appear in events or limited treasures.

A limited treasure is a temporary treasure in the Recruit interface and it only appears for a period of time and disappears. Back in November-December 2016, there was a kazekage limited treasure that had kazekage gaara in the treasure. In the China server right now, they have three limited treasures that have edo jinchurikis only until December.

Nobody on China haven't bother using any ninjas from these edo jin limited treasures so you shouldn't worry about getting them. Also, they may or may not end up in a permanent treasure on their own just like how the kage treasure has kazekage gaara as a rare when he appeared in his own limited treasure.

Edo hiruzen/edo asuma/edo tobirama are event exclusive so you can't spend seal scrolls on them.

There's no other new treasures at the moment besides GNW so if you have all the ninjas from the treasures we have so far then start saving. Even if the China decides to introduce a new treasure, we shouldn't be seeing it for about 1-2 years if Oasis decides not to speed up the updates and follows the same timeline that the China is on.