Main Changes in the 7.0 Legion Pre-Patch
The first thing to cover is the removals of the pre-patch, which you can find below:
Challenge Modes: The Warlords of Draenor challenge modes will be removed in 7.0 and will no longer be available for completion. This means that you need to complete them before 7.0 if you want to earn the title, mount and weapon transmogs.
Raiding: The changes to Hellfire Citadel will happen in 7.0, with the Cutting Edge and Ahead of the Curve no longer being available. This also means the Grove Warden mount will no longer be obtainable.
Brawler's Guild: The Brawler's Guild Season 2 will end, but this time it won't come back straight away. It looks like the developers are hoping to give it a bit of a makeover before releasing it for Season 3.
Currency Changes: Just as we saw Valor Points and Justice Points being removed, the Honor and Conquest points will also be disappearing, most likely turning into gold as they normally do.
Heirloom Trinkets: The trinkets that drop from Mythic dungeons will no longer be available.
Legendary Ring: The ring questline will no longer be available to start, but you can still complete it if you have already started.
PvP: Season 3 will come to an end with the pre-patch.
Glyphs: We will no longer have any major glyphs, given the coming changes to the glyph system.
Garrison: The gold that you receive from your garrison missions will be nerfed hard in the pre-patch, as well as the Pet Charm droprates.
While we can see many of the general culprits above, including Challenge Mode removals and season ends, it's not all bad news! There's plenty of new content coming with the pre-patch, all of which will line us up to prepare for the invasions. Here are some of the major changes that are coming:
New class/race combination: The Gnome Hunters will indeed be prowling the streets, waiting to capture the biggest pets they can!
Class Trials: These will allow you to try your new class before using a level 100 boost, just to make sure you're choosing the right thing!
Pre-patch event: The pre-patch events will be happening across the world, including invasions and the "mind-control" events.
Transmogrification: The new wardrobe system will be implemented, which will finally allow players to clear out their banks and void storage of the countless sets they have collected.
Secondary Stat Removal: With Legion, we will be seeing the removal of a number of secondary stats that are either being standardised or removed, such as Spirit, Multistrike and Bonus Armor.
Gold Cap: The gold cap is going to be increased, as well as the cap on bids for the Auction House and Black Market, to 9,999,999 G.
Extra Character Slot: In order to accommodate the introduction of the Demon Hunter, we are going to be given an extra character slot, raising the total to 12.
User Interface: All of the new quality-of-life changes to the UI in the beta will be introduced with the pre-patch, including the new health bars, animations and so on.
Challenge Mode Item: Despite the Challenge Modes being removed with the pre-patch, a new item will be added that allows you to unlock the Warlords of Draenor Challenge Mode transmog looks on every character, if you have completed them on Gold already. It will cost 3,000 G.
While this last change isn't necessarily coming with the release of the pre-patch, it's going to happen at some point before Legion launch.