A huge space migration can translate also into even greater pain - spaces can get so big that will cause attempts to do the XML export/import to crash.
For a huge space, admins have to devise their own migration tools or suffer from long and painful migration steps (long-running exports, for invalid characters in the files inside the backup zip file, long-running import, etc).
Today the XML format is used for the main file (entities.xml - which can take an absurd side) and a few other files/directories and the attachments directory.
The suggestion is that this process can be refactored to bypass file sizing limitations by
- using other formats (non-XML), easier to parse and work with (and potentially smaller in size)
- implementing a wire migration tool that'd allow a space to be transported to another instance
Essentially the way to improve it is not the main thing - the main ask is to actually improve the space migration task to make it easier and faster for really large instance admins.