Preparing for 365

Thinking aloud here are a few comments! I think it comes down to what does the organization want to achieve, what are its goals and how can Office 365 help. Organization culture and preparedness, adjusting to Office 365 and the toolset it brings is also important. Be aware that Government tenants (if that’s what you will be on) won’t necessarily have the latest features.

Yammer might be a great testbed, since you're already involved with it, with the concepts of collaboration and what the Yammer folks call the "outer loop" for driving teamwork. Check out the recent Build your outer loop: What's next in Yammer blog post for details.

You may find the biggest barriers are more to do with not the technology, more how adaptable staff are and the resources you put behind it.  Training is very important, champions etc, look at the https://fto365dev.blob.core.windows.net/media/Default/DocResources/en-us/Office_365_Adoption_Guide.pdf for lots of practical tips and guidance for putting a framework around your Office 365 adoption.  If you are looking for inspiration, this collection may be of interest as well - https://gallery.technet.microsoft.com/Office-365-Productivity-de7da48a.

I'd suggest setting up an Office 365 dev tenant, if you haven't got one, you can https://social.technet.microsoft.com/wiki/contents/articles/37830.office-365-how-to-set-up-a-free-developer-tenant.aspx.  If you are still getting up to speed, try out new features, since you use SharePoint on-premise, if you haven’t already, try out modern teams sites and communication sites, as well Office 365 Groups, Microsoft Teams etc.

Also, see some of the items in the "https://academy.techcommunity.microsoft.com/pathways/learningpath/7e4897d4-bcb2-44c4-ab3c-0b634a1c968a" learning pathway in the new Microsoft Tech Academy. 

Hope that helps a bit.