Those have to happen if Musk has any intention of fulfilling some of the things he has said so far. He is repeating over and over that one of his goals is Mars, and while Falcon Heavy can carry Martian payloads, it doesn't quite cut it. This and the other things that he have been mumbling are strongly suggesting that he intends to work on those (or similar ones) once he gets the opportunity.
If the FH can loft 53 mT payloads, you can be sure that is is enough for a Mars program. Many other technologies will be required, sure
- but lift to LEO will not be a bottleneck.
The point that many SLS detractors (such as myself) often try to make is that we should cancel SLS, and spend that $$$ on in-space and mars-related hardware. Using commercial crew and cargo to LEO should allow NASA to build actual exploration hardware - because right now there is *nothing* in the works. SLS and Orion is taking up all of NASA's development budget - and once they are completed they will have nothing to do for years, since there is no payloads/mission hardware in the works at the moment.