"The hopeful depend on a world without end
Whatever the hopeless may say."
Rush - "Manhattan Project"

We used to pray that more, "world without end."

"in saecula saeculorum" ... has a nice ring to it. Whether or not it's eschatologically accurate¹ is a matter of interpretation, I suppose.

What one means by "world".

But it concludes the Gloria Patri that opens the Tridentine Ordo:

Gloria Patri, et Filio, et Spiritui Sancto,
Sicut erat in principio, et nunc, et semper, et in saecula saeculorum.² Amen.

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¹aion ("for ever and ever") in Revelation (14 occurrences - KJV).
²in saecula saeculorum ("for ever and ever"), in Revelation 1:6 (Jerome's Vulgate).