Re: What happens if I switch to an origin account that doesn't have the same DLC?

@Synzorasize - If I were you, I would make a backup copy of your TS4 documents folder, and put it somewhere safe to use for when you have the dlc's. (Your friend was right, it's against the ToS to share accounts, so getting everything sorted now is a good idea)

So, backup your sims files following instructions Here. Then, with all your content safe, go ahead and open your games in the base game. You will receive a message that says something like "content used to create this game has been removed". Then all the different pack stuff will be gone. I don't know if things like occult sims will be removed entirely or reverted to regular sims, but I would guess that the sim is no longer available. 

So, you could go into a save and see what it looks like. You'll, of course, need to rebuild / redecorate / redress a bunch in your existing games. Or you could just start a fresh new game. You're not going to hurt your original saves by working with a copy, and there may be some that you can salvage. Worst case scenario - just start a fresh, new base game and wait for the sales to access your other content. But at least you can check to see how much work it would be to continue with the older saves until that happens.

Happy Simming!