Oh, in that case yes you will need at 2016 CU3 for teams hybrid integration for on-prem mailboxes.
https://learn.microsoft.com/en-us/microsoftteams/exchange-teams-interact
But I think the question is what is the plan for the mailboxes?
If you are going to move all user mailboxes to Office 365, then there is no real "benefit" to using 2016 or 2019 to do that. Mailbox moves will work regardless.
If you are planning to have mailboxes both on-prem and in 365 for a indeterminate amount of time, then I woudl upgrade to 2019.