We have run into many scenarios where a company has Office 365 and then orders Dynamic 365 from a CSP (Cloud Service Provider) and their systems end up different tenants.  As Microsoft moves to the model where there can be more than one partner of record and various flavors of Dynamics 365 (Finance and Operations, Business Central, Customer Engagement, etc..),  I can see this problem getting more prevalent over time.

When your Office 365 and Dynamics 365 are in different tenants it becomes quite the challenge and inconvenience.   A few major issues are as follows

1. Server-Side Sync – only supports single tenant.
2. Single sign-on – need to log into two systems.
3. Two systems to manage
   1. Users
   2. Licensing
   3. Notifications
   4. Double the security concerns
   5. Double the competencies efforts
   6. etc… 

You say, heck this is easy, let’s just move our Dynamics 365 to the other tenant.  If it were on Premise it would…

Microsoft is adding more AI-infused Dynamics 365 applications to its line-up. In addition toe the previously announced Dynamics 365 AI for Sales app, Microsoft also is introducing a Dynamics 365 AI for Customer Service app and a Dynamics 365 AI for Market Insights app this fall, officials said on September 18.

Link: Microsoft adds two more Dynamics 365 AI apps to its roadmap
via http://www.zdnet.com

Do you know that you can influence the direction of Dynamics 365? But you may be unsure as to whether it really will make a difference. Microsoft have a site where the community can add ideas and vote on them. Go to https://experience.dynamics.com/ideas/ and create your ideas. If the idea is valid and they get enough votes, Microsoft will act and include them in their product backlog. But equally important is the ability to vote on other’s ideas.

• Voting is the most important way to make the community voice heard on the issues that concerns the roadmap for Dynamics 365.
  
• Voting gives you an opportunity to be part of the priority that affects Dynamics 365.
  
• If YOU don’t Vote Others will make the decisions for YOU!
  

As we speak, there are 1673 ideas for Microsoft Dynamics 365 for Finance and Operations and 212 ideas for Microsoft Dynamics 365 for Retail