Good question, but also a hard question. I'm curious for the answer of course, but I'm not sure, if there will be an answer anytime soon. But in the meanwhile I can give you and other readers an educated guess:
1) Unfinished Integration
The integration of the OnlyOffice document app and the presentation app are still work in progress / beta, so I assume that the CryptPad team will finish this before working on an OnlyOffice upgrade. This integration was announced 3 years ago, in october 2021. So it's either complex (of course it is) or they are underfunded or both. So I take this as a hint for usal solving time.
(https://blog.cryptpad.org/2021/10/21/Announcing-new-apps/)
2) Past
In the past the Cryptpad team upgraded OnlyOffice roughly 1 year after the OnlyOffice release (according to samples I reviewed). OnlyOffice 8.0 was released 10 months ago, in January 2024.
3) Roadmap
I see no current item for an OnlyOffice upgrade in the roadmap. There is an item "OnlyOffice Integration Improvements" (with keyword "france 2030", the investment program of France), but I think this means points like finishing doc and presentation integration and refactoring the code concernign OnlyOffice to save time for future code changes - like OnlyOffice upgrades 😉
(Roadmap: https://cryptpad.fr/kanban/#/2/kanban/view/PLM0C3tFWvYhd+EPzXrbT+NxB76Z5DtZhAA5W5hG9wo/)
(Refactoring: https://github.com/cryptpad/cryptpad/issues/1469)
4) Major Version
Since it is a major version change (7.x --> 8.x) I think this may take more time than a minor version upgrade (7.x -> 7.x).
5) Release Cycle
There are 4 CryptPad updates a year, each at the end of a quarter.
(https://blog.cryptpad.org/2024/03/29/status-2024-03/)
So my educated guess is release 2025.3.0 or 2025.6.0.
Prove me wrong and ship it with 2024.12.0, but I don't think so :-)
