AFAIK, the main obstacles are

the toxic soil, due to high levels of perchlorates (shipping soil would be prohibitively heavy and, given that arable land might come at a high premium in the coming century, might be a bad idea)
high radiation on the surface due to lack of magnetic field,
high energy requirements to combat the cold and lack of energy sources (due to distance from the sun and the presence of dust) which would probably require nuclear reactors and their fuel (which are extremely heavy to ship)
dust, which is a health and mechanical hazard
low gravity
shipping enough people is prohibitively heavy too
an enormous supply chain to produce and ship all that material from Earth to Mars

Solutions to these problems like space elevators to get rid of the rocket equation, new medical fields built from scratch, artificial wombs, energy production, closed biosphere management count, in my book, as discontinuous tech progress if you want them short term (a century). This also looks like a 'big bang' project management approach in which we have very little time to gather feedback on unforeseen problems which an incremental and long term approach would provide. Big bang projects carry a very high risk of failure and wasted resources (and we are talking a lot of resources here.)

An incremental, long term approach would require sustained, heavy efforts over the course of several centuries which, again in my book, does not count as the foreseeable future.

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