The problem with the sorcerer in 3e was that there was little to differentiate it from the wizard. Oh, sure, he had a limited number of spells known and was able to cast spontaneously (which I love), but what was his identity? When the magister appeared in Arcana Unearthed/Evolved, it became apparent that the sorcerer was no longer necessary.
The idea of bloodlines, as seen in Dragon and later Pathfinder, is a great way to provide some of that identity. If wizards focus on schools and sorcerers on bloodlines, you have a winning combo.
The 4e sorcerer had a lot of good things going for it, and I particularly like the chaos sorcerer build. However, I felt it didn't hold its own compared with strong archetypes like the wizard and warlock. Perhaps I'm being a bit down on it.
I don't know what the sorcerer will be in 5e, but I do know that I don't want it to be a variant wizard. I would rather see some focus on elemental or wild magic, or bloodlines. Give the sorcerer identity so that it can stand on its own.