Here I'll try to list the best upcoming features for SharePoint Online. First of all I just have to say there has been loads of news. Let's get right to it:
Hub-sites - a new site to group Team-Sites and Communication Sites. News, documents etc will show up in the hub-site. It's also possible to "detach" sites from the hub-site and the news/documents etc will no longer be shown on the hub-site. Neat!
New Admin Center - we are finally getting a new and updated SPO-admin center. 'nuff said
New search - you can now filter even more on the search, which looked really nice and you can also preview the results. You can also search right away from a user card and for instance search in all their public (or rather files that they have shared with you).
LinkedIn integration - to be honest, I wasn't really thrilled about this until I saw it. In the people/profile Add-On you will now get a nice LinkedIn integration with information about the user you have looked up.
Conditional Access for Sites - now it's possible to block certain resources and/or make them readable if the user is accessing it from an unmanaged device or whatever you decide.
Region specific policies - it's now (soon) possible to set rules for specific regions.
Mobile App - a lot of work is being done to the Mobile App.
Latest documents in App-launcher - not so much to say about that ;)