Getting less abstract: there are no real technological hurdles for eliminating emissions for personal vehicles, and probably-manageable ones for other surface transport (cargo shipping, etc.). Decarbonizing the electric grid has some technological challenges to solve (mostly around intermittency and storage if we go all renewables, or cost if we go mixed renewables and nuclear), but there are reasonably clear paths forward. On the other hand, we really don't know how to do zero-carbon long haul aviation, or concrete production and curing, or aluminum smelting, or trans-oceanic shipping -- maybe portable/modular nuclear could be used for the last two, but it's still pretty pie-in-the-sky. So, maybe in the future we have electric cars but carbon capture for long-haul jets, or something.
(Aside: the recent Bill Gates climate book has a pretty thorough rundown of all the major current emitters and the levels of technological readiness for decarbonizing each.)