Short-term future forecasting (months to years) is practical, because it could be reasonably accurate.

Mid-term future forecasting (many decades to centuries) is entertaining because it is most likely inaccurate, but we cannot argue with the author since none of us will be around to check.

Long-term future forecasting (thousands to tens of thousands of years) is plain crazy and meaningless.  Forecasting forward for as long as mankind has existed seems completely meaningless, lacks scientific merit, and is for entertainment purposes only.

How about forecasting forward millions to billions of years?

The most interesting part of the video below is that it puts time in perspective by linking it to the amount of energy under our control and discussing the amount of time needed to reach each control level.