Why can't the URL to a SharePoint Online site be changed to a new domain name?
Unfortunately with Office 365, if you merge with another company or change you company name, you have to start all over with a new billing account and manually migrate email and shared documents on SharePoint just to change a domain name. Many companies merge or change names. This should be easy.
Andrew Stuart commented
Understand the difficulty especially with shared files however should be a basic process as many companies change names.
Gabriel Machado commented