Why would one need a model out 100 years? First, they have shown to be completely inaccurate as the models have never been validated. Second, thought the world was going to end in 12 years? Why bother with what might happen after that?
To show that the models are reliable for 100 year, they would have to accurately predict temperature from 1918 to 2018, given the correct inputs. Then, if the model accurately predicts 2019 to 2024 using the actual data from 1924 to 2018 and assumed inputs from 2019 to 2024, they may be on to something.
Do I really think this will work? No, because no model will have all of the necessary inputs to correctly predict even what has come before, the assumed conditions may be completely wrong, and that climate modeling is a huge set of non-linear equations that are sensitive to initial conditions (chaos theory).