Microsoft hasn't communicated any new formal deprecation of EWS as a whole, only certain API's within it, which aren't used by CUC. Per MS's announcement last year, they changed their initial stance on removing it and are still keeping it around after the feedback they received: https://techcommunity.microsoft.com/t5/exchange-team-blog/upcoming-api-deprecations-in-exchange-web-services-for-exchange/ba-p/2813925
"We strongly urge our ecosystem partners accessing Exchange Online data to migrate to Microsoft Graph APIs."
They're going to try suggesting Graph, but nothing changes with CUC as it stands now. The only change made recently with how CUC functions with O365 was the implementation of Client Credential grant flow instead of ROPC. This is explained in the 14SU3 release notes: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/readme/b_14su3cucrn.html#Cisco_Generic_Topic.dita_b23c4c0e-0e88-459d-91ca-7833fcffbd8b
Cisco works closely with Microsoft, so until you see something from Cisco indicating changes with the integration, everything is business as usual.
Hope that helps,
Brad