I don't see Jace, the Mind Sculptor ever being legal in Modern

Anything is possible, especially if new cards need to be pushed as was the case of the broken Eldrazi decks displacing the equally broken Splinter Twin deck, but JTMS, IMHO, is in a different category. JTMS by itself is a card that will push a whole color, not just a strategy. I would love to see it in Modern, because I have a playset online I can only play in the two dead formats (Legacy and Vintage), BUT, I just don't see it happening, like ever.

Here is the argument: JTMS has a zero ability that is the same as a repeatable Brainstorm. Do you see Brainstorm being legal in Modern? Not ever. There is even a strong argument to ban Brainstorm in Legacy. Well, with JTMS you get a repeatable Brainstorm AND you still have three more abilities.

Even in Legacy and Vintage, JTMS sometimes enables me to take over complete control of the game. The +2 is making my opponent's strategy dead in the water. 'Hey, you really need that land, how about I put it at the bottom of your library.... hey, you need this card to combo-off, how about I put it at the bottom of your library.' You get the picture. Oh, and I am +2 every time I do this... insane power.

As an aside, some people think JTMS was a design and development mistake. I think not. I think every TCG needs a JTMS, and Yugioh and Pokemon, rightly, have always had their equivalents. It sells packs, and it sells the game. In very small quantities, broken cards are great for a TCG.