The slope is still slope, because it will always be a slope. No matter what they sell. They might sell HC ilvl boots and bracers, and people will see that it is only a time saving thing, since you can mindless mine & herb for 200 hours (no need to learn how to play the AH, easier than leveling, only time consuming!) and get enough gold to buy them on the Black Market. They might sell HC tier and weapons, titles, reward mounts, and hey, it will be no more than a time saving thing, because you could again mine & herb for 1000 hours and buy boosts from HC guilds.
They just need to slide slow enough.