World of Warcraft: Battle for Azeroth's pre-patch arrived a couple of days ago, bringing with it a whole bunch of changes. Most notably, it introduced a massive stat-squish in order to curb the inflation of damage and health numbers as they were getting somewhat out of hand. While the patch has successfully managed to do just that, the unfortunate side effect was that the leveling process ended up being even slower than before.
Thankfully, it would appear that Blizzard is well aware of this, as noted during the most recent developer Q&A. According to the Q&A, the WoW team did not intend to make leveling more difficult with the latest batch of changes, and is now actively investigating the issue. No concrete fixes have been announced just yet, but the goal is to make the leveling process feel just as fast as it was before. Personally, I would prefer it if they made it even faster as the 1-110 leveling experience has been incredibly slow since the dungeon changes, but at this point I'm willing to take anything to help speed the whole ordeal up.
As for the future, you'll be glad to hear that the team is also considering a level-squish. After all, telling a brand new player that they will need to go through 110 levels before they actually reach current content is never going to go over well, and that's a problem that will only grow larger as more expansions come into play. Another problem with the current system is the lack of rewards throughout leveling, with everything from level ~40 to level 110 being a wasteland in terms of new abilities or effects to play with.
Naturally, nothing concrete has been announced just yet, but it does appear that the team is seriously considering the idea. That said, given how enormous of an undertaking this whole system would be, I don't think we'll be seeing a level-squish until after Battle for Azeroth itself.
If Blizzard decides to release any more information, or if they finally patch in faster leveling, I'll make sure to let you know. Until then, you should check out the Q&A over here as it offers some great insight into how the WoW team works.