What is the impact of the metadata methods on the Appian plugins in 7.10?

Would you mind explaining in more detail if you mean the fact that the Metadata engine has been removed? (forum.appian.com/.../Appian_Release_Notes.html

If that's the case, there shouldn't be any impact since those methods were not widely used and they were deprecated long time ago meaning developers should have updated their code already, but I really doubt someone was using those methods since they were not useful.