Are you referring to merging EA Accounts, or shared progress between different platforms (e.g. Steam, PlayStation, Xbox)
Cross-Progression already exists, meaning that all platform accounts linked to one EA Account share the same progress.
More information about that can be found in this video: How Cross Progression works in Apex Legends | EA Help
If you are talking about merging different EA Accounts, then I believe that would be quite unlikely to be ever implemented, as this would also be impactful for all other games that have progression. Of course, never say never, but personally I think the chances of them ever implementing something like that is near 0%.