Calculating or simulating how earths magnetic field behaves or is generated is quite a complex task. So im doubtful we can usefully estimate it to such precision. It would be interesting though.
We know how weather works quite well, but knowing if it will rain in a week is an entirely different beast.
My memory is that the calculation found that if humanity switched to geothermal for all its energy needs, then in only about 1000 years, the core cools enough for the magnetic field to stop, but I am not sure.
(We should definitely deploy geothermal in the Yellowstone caldera though long enough to cool it down enough so that it will not erupt again.)
Humanity could max out geothermal for a million years and never make a dent.