Current wantlist throughout all collections is approximately 173,000 cards.
As Jim suggested, somewhere between 150,000 and 200,000 (no one is sure of the exact number), you can no longer take advantage of the "Add All Missing to Wantlist" function. It must be done on a card by card basis.
Edit to add that contacting Admin works for technical issues, but this is a known site function. The limit before mass-adding was disabled used to be 100,000, and it was raised to 150,000 at some point. I doubt that he will raise it again, but with the new server, perhaps someone can submit a new feature request.
I'll never quit collecting entirely, but I am downsizing. Check out my COMC store and help me thin out what I don't want so I can buy cards that I do want. See something you like? Send me a message on here, and we can knock the price down quite a bit. I'll even take a bit of a loss if it means getting you a card you really want.