My view of things...
The EF 50mm f/1.4 people expect from Canon is part of a new category, started with the Zeiss Otus 55mm f/1.4, Nikon 58mm f/1.4, and Sigma 50mm f/1.4, all announced within the last three quarters. It should be a Canon EF 5Xmm f/1.4 USM (might be IS-less) priced at ~U.S.$1,500
As others wrote above, none of Canon's 50mm are in this category. The f/1.8 is a cheap kit lens, the f/2.5 is a macro lens, the f/1.2 is a portraiture lens, and the f/1.4 is in the wrong price bracket.
My guesses are:
1. The f/1.8 is here to stay.
2. The f/1.4 will get the 24, 28, and 35 treatment (IS, ring USM, etc).
3. A new f/1.4 to fill the spot. If people want to buy, it's good business sense to sell.
4. The f/1.2 will stay beside the new f/1.4, even though sales might take a hit.