One of the things that I love the most about Brandon Sanderson is his laser-focus on unique characterization, never sacrificing who a character is to perpetuate some contrived notion about "how things should work." I think we can be very confident that if he DOES initiate a love triangle of some kind (honestly, it seems REAL unlikely in this case) it will be as a natural outgrowth of the characters, not as some disappointing, half-cocked literary fast food that gives no satisfaction.
Vin's journey with love is exceptionally poignant because of who Vin was, and the perfect and unique foil that Elend was for her, teaching her to be different than she was. Even though it is obvious that Elend and Vin will end up together from almost the first second we see a unique young man reading at the ball, it doesn't feel contrived or arbitrary because of the way Brandon uses their relationship to push them both to be new and improved people. Frankly, this is what a real relationship does, which is why it doesn't feel as "love-triangle-ish," while other literary relationships fall flat because they seem forced.