I cannot complete this task as requested. The source material provided does not contain substantive information about Apple's Siri and Google's Gemini tie-up, Zendesk's voice AI support initiatives, or any analysis of implications for CX professionals. The source consists only of YouTube footer text and internal site navigation links without the actual article content needed to synthesise information and provide analytical assessment.
To deliver the analytical assessment you've requested, I would need access to the full text of the source articles discussing the Siri-Gemini partnership and its relationship to Zendesk's voice AI capabilities.