When it comes to Classic, Blizzard's goal is to provide an authentic Vanilla experience, but they also needed to come up with technology to handle many players at launch, which is similar to sharding. While the use of this technology will be limited to the first month following launch, many players are questioning this decision and wouldn't like to see layering in the game at all.
Occasionally it's also been proposed to re-randomize all the gear. We didn't have best in slot lists back then. People weren't starting out as a fresh level 1 character with a complete list of which dungeons to run at 60 in order to gear as quickly and efficiently as possible. Now, all that data is available. If gear were re-randomized then all of those lists would become useless and thing would be close to how they were. Which is a more important part of the "vanilla experience?" the fact that item X from boss Y has exactly Z stats on it, or the voyage of discovery? Personally I think that voyage is way more important. Do you remember how many points of which stat on the ring or whatever that Darkmaster Gandling drops? I don't. Would it kill your experience if the BiS for every class were in a different dungeon so people had to actually play to figure it out rather than simply consult a spreadsheet? I don't think it would. For that matter, it probably wouldn't be a bad idea to handle it intelligently so that the better gear is in later dungeons. I remember there because some weird cases where level 40ish gear was better than anything that dropped in level 60 dungeons.
Within the context of Classic, the method most frequently proposed is to re-tune bosses to make them harder. Rather than copying the numbers, re-create the relative difficulty. Kind of like, when you first start working out, you use small weights. When you get stronger, you lift bigger weights. The WoW community is more knowledgeable, more experienced, has better hardware, etc. We're "stronger." So give us tougher bosses. There are a lot of forms that could take. Bosses were constantly re-tuned during vanilla anyway, so if Ragnaros does 10% more damage or something, is that really a problem? I don't think it is. What about resistance gear? back in the day, collecting resist gear was a thing people did. But the numbers and strategies are so well known today that only the tank really needs it anymore. Bosses could be re-tuned with more resistible elemental damage so that's important for entire raids to gear appropriately. That would be entirely keeping with the spirit of vanilla even if the actually numbers sitting in a database somewhere were different than they were ~13 years ago. If you want to go a little farther, a few people have proposed adding new abilities to old bosses, adjusting their timing, etc.

The inker leaned forward, and something so hot it was cold, or perhaps so cold it was hot, touched Vandel’s flesh. He fought down the urge to scream. When the needle withdrew, he felt as if a dagger were being pulled from a wound and twisted. No. No. No. The void in his head gibbered in panic. The fear communicated itself to him. This was a trap. Evil magic was being worked here. The needle stabbed in once more. Pain blasted his body, worse than anything he had felt since he had pulled out his own eyes. He thrashed around, trying to free himself. The restraining bands drew tight. Hard hands pushed down on him. The needle stabbed again and again, and every touch of its point sent blazing agony searing through him. With every stitch, strength leached out of him. The voice in his head grew weaker and weaker. He was dying. This magic was going to kill him. He snarled threats and whimpered pleas, but the pain went on and on and on, until he could struggle no more and only lie there while the inker went about his work.

The system is automated, meaning that once slots are available, beta testers will be chosen, without any beta key to speak of. Kaivax then goes to stress the importance of your account security, stating that, “any third-party e-mail messages, websites, or in-game whispers that offer beta keys or access to the WoW Classic Beta should be considered illegitimate and ignored or reported.”