Azure FIM for on-prem

Hi,
 We have ADFS in our Onprem and we are planning to setup up ADFSP for Office 365 SharePoint. this also require Dirsync. 
so we need to add three additional servers. two ADFSP and one FIM. 
Main challenge is cost and we are trying to reduce it. 
Now we have SalesForces hosted on Azure platform where we have Ad, ADFS, ADFSP, FIM. this is completely separate external environment and not connected with on-prem. 
Question is can I use FIM sync hosted on Azure for my Office365 SharePoint requirement? can I connect my internal AD to Azure FIM and then Office 365 SharePoint ?

Thanks in advance.