Having somewhat gone round the houses with this with a hybrid deployment recently as both:
- High-resolution Contact Photo in Lync 2013 client and Lync Web App.
- Archiving Content (IM and Meeting) in Exchange.
Are supported with Lync Server 2013 On-Premise with Exchange Online per:
Supported Lync Server 2013 Hybrid Configurations
Both of which required Unified Contact Store (UCS) which has a prerequisite for Oauth.
Exchange Server and SharePoint Integration Support
“Server-to-server authentication between an on-premises server and an Office 365 component is not supported in this Lync Server 2013 release. Among other things, this means that you cannot set up server-to-server authentication between an on-premises installation of Lync Server 2013 and Microsoft Exchange 365.”
Note: “this Lync Server 2013 release” having opened a support case Oauth is not currently possible.
So it maybe following the O365 upgrade/transition from 2010 to 2013 is completed and/or another update to Lync Server and/or Office 365.