Yes, it's still possible! As long as your CCNA Voice certification is valid, you would only have to pass the 210-065 CIVND exam to convert it to CCNA Collaboration. If your CCNA Voice certification expires before you can convert it, then it will be necessary to complete all of the current CCNA Collaboration requirements to achieve the certification.
You can review the CCNA Voice to CCNA Collaboration FAQ for information as well. Good luck!
Cisco Learning Network Moderator