Get estimate of Outlook Anywhere users

We are planning on adding a new primary authoritative domain in Exchange 2010.  Most of the mail clients are using Outlook 2016(connected both internal and external)(we also have Active sync devices, Apple, androids etc.. and a few OWA users).  We would like to make the existing Primary SMTP address an alias address.  First steps would be to add the new UC certificate with the names(for autodiscover.domain as well), add the accepted domain and modify the default email policy(Virtual Directories can stay the same since we are not changing the OWA URL).  

The concern is for Outlook users, will internal users existing mail profile update on its own?  And for Outlook Anywhere and activesync users, do the profiles all have to be manually recreated?  If so, we would need to plan for extra staff accordingly when we go live, so I am trying to roughly determine how many users are configured to use Outlook Anywhere, nothing exact, just a rough estimate.  I checked in the IIS logs but cant really confirm which log entries are Outlook Anywhere. Is there a specific string to search for in the IIS logs?

Thanks!