The SWTOR Developers are looking into implementing legacy wide datacrons. If all goes right, this might be included in the upcoming Fallen Empire expansion.
Datacrons Are For Legacies | 08.11.2015, 02:48 PM
I wanted to pass on a little tidbit that I heard this morning. We are very actively looking to put Legacy-wide Datacrons into Knights of the Fallen Empire! We know this has been widely requested for many years and so the Design team is working as we speak to get it in.
As always, this is not a guarantee that it will make it in, but the team is hard at work to make it happen.