Revamping Scholomance removed one of the most valuable monsters in the instance.
This is good news!
Check your banks
If there's any of these formulae (Not Scrolls) for sale in the auction house currently, you should buy them out if the price is reasonable. Not many are aware of this formula no longer dropping and sell them for as low as 100g-500g each if they have some in bank.
If you already know the enchant, selling scrolls should have significantly less competition, allowing you to make faster sales and make more gold overall.
Use caution though, as it's not the first vanilla enchant formula that gets booted. Perhaps the most well known example is the Crusader enchant, it too got removed from the game for a while, but eventually reappeared, although in a different location.
However, as Lifestealing enchant is not a very popular one, it might get completely ignored by Blizzard. In any case, once the AH is out of stock, you should list yours for say.. 30-100k gold each, one at a time, but only when no one else is selling or you will have a war going on.
Even if it gets added back to the game, it will take at least a month and the drop rate should become significantly lower.