Not sure why people keep linking speculation topics on a third-party site. That is right, the topics on wowhead are speculation and guesses based on things they datamined. During PTR, things are changed and these guesses aren’t always updated. Also Blizzard does try to keep information hidden and will change things at the last moment so they can’t be datamined. Who knows, maybe people will get lucky and get a 425 Titanforge from a Warfront or lower level Raid.
Here is the topic you should refer to when you’re discussing the scaling in 8.1.0 -
I don’t really expect any changes to happen to this until 8.1.5 is released. There is no need for a catch-up mechanism for Heroic raiding now. You can start this with the mixture of 400 and 385 ilevel gear already available to everyone.