Profession changes in 8.2.
All Battle for Azeroth professions will have their skill cap raised from 150 to 175. With Patch 8.2 going live on June 25th, be sure to visit the Darkmoon Faire the week of July 7th and complete the quests there to increase your major and minor professions by +5.
All of the new profession skills in Rise of Azshara rely on new materials (except for Enchanting at this time). With the exception of Spare Parts and Ionized Minnows (cooking ingredients found only in Mechagon), the new materials are only found in Nazjatar. See the Wowhead article
for more details on professions.
For your major professions, if you are already at 150, all of you existing patterns will have greyed out so you will have to visit a trainer to learn new patterns in order to further advance your profession. Currently on the PTR, the profession trainers in Boralus don't have the new patterns, but hopefully this will be changed. If not, there are trainers at Mezzamere in Nazjatar (38, 53.5) that have the new patterns.
One good thing about the new patterns (unless they "fix" it) is that none of the new patterns require materials from dungeons or raids. What this means is if, for example, you have an Engineering or a Jewelcrafting alt which you normally don't run through mythics or raids, they will be able to make some nice BoP gear which they can use. Engineers can make 415, 430 and 445 BoP Azerite helms and Jewelcrafters can make 410, 425 and 440 BoP rings with sockets (unique equipped). Also Alchemists will be able to make 410, 425 and 440 BoP Trinkets with sockets. As for Blacksmiths, Leatherworkers and Tailors, they can each make two pieces of 410, 425 and 440 BoP gear and they all come with a socket. As for Scribes, they don't have any new BoP equipment, but they will be able to make four different 400 BoE trinkets which are better than any other crafted BoE gear.
It's likely that the new Osmenite Ore is going to be in high demand as it is used by Blacksmiths, Engineers and Jewelcrafters.
One thing you can stock up on in preparation for the patch release is Epulsom as both the new BoE and BoP gear require a fair amount of it.
Update: OK, well they did manage to screw it up. What they did was require that you obtain various levels of "Abyssal Focus" before you can craft the 410-440 BoP gear. This starts with picking up a "Broken Power Core" in Nazjatar at 38.1, 36.9. Turning in the power core leads to the quest "An Abyssal Opportunity" offered by Instructor Ulooaka in Mezzamere. This quest requires you to obtain 15 Abyssal Shards which can be purchased from Artisan Okata (also in Mezzamere) for 5 Prismatic Manapearls each.
What this means is that you have a choice of acquiring and upgrading Benthic gear using Manapearls or spending 75 Manapearls on this quest. Note that it takes a total of 190 Manapearls to upgrade a single piece of non-azerite gear from 385 to 425.
Completing An Abyssal Opportunity creates a "Restored Abyssal Focus" at 37.49, 53.35. Standing next to this allows you to craft the 410 gear.
Completing this quest leads to another quest "The Eternal Palace: We Can Make It Stronger". This is where they brought back some raid requirements. For this quest you need to "collect 20 Eternal Ornaments from the most powerful creatures of the Eternal Palace". We'll have to wait for the Eternal Palace raid to start before this can be tested. It may not be too bad if the Eternal Ornaments can be collected by running Raid Finder (but don't hold your breath).
Completing this quest should create an "Empowered Abyssal Focus" so that you can craft the level 425 gear. You learn these patterns after crafting the 410 gear.
From what I've read, there is a similar quest requiring 200 Ethernal Ornaments to create a "Radiating Abyssal Focus" so that you can craft the level 440 gear.