If it matters to you how likely your future scenario is to be realized in a particular timeframe (and I’m not saying it should matter to you, but if it does), here are some basic guidelines for figuring that out. They’re not actually expressed in the form of rules, despite the headline.

https://spectrum.ieee.org/at-work/innovation/the-rodney-brooks-rules-for-predicting-a-technologys-commercial-success