No one but the developers know what is in RM8 for TreeShare.
When TreeShare was first released, both the developers and some beta testers opined that TreeShare was better than TreeSync because it allowed the user control over the transmission of data between RM and ancestry to avoid data disasters that might accrue from a true TreeSync. Indeed, former FTM users have told stories of data disasters that were caused by problems with FTM's full blown syncing between FTM and ancestry.
I for one would love to see at least a full-blown one way TreeSync from RM to ancestry. I also will never sync or share anything from ancestry back to RM. Or if I did, I would only do it with a temporary RM database that I could examine carefully before moving the data from my temporary RM database to my permanent RM database.
There are many problems with the whole TreeShare concept. Some of them might be able to be improved upon by the RM developers. Other of the problems would be difficult to be improved upon. The reason for the difficulty is that RM and ancestry use very different data models. So both systems have data that the other system has no good way to store, and it's difficult to translate RM's family facts to and from the way ancestry handles marriages.