On some objects, there are a lot of fields. It would be really useful from a user experience point of view to allow multiple tabs for record detail component in lightning. Each tab can be associated to a Page Layout Section (may be) or the admin can drag and drop fields on to each tab and customize the tabs.
Ofcourse, R&D would have to research on how to properly show field Validation Rule errors, and the placement of Save and Cancel buttons. But this feature would really be useful from user experience because right now Lightning Experience takes a lot of time load the page. Having ability to breakdown fields into different tabs, will be really great.