Roadmaps, for companies that decided to use them, indicate proposals, that's all.
Executives and boards decide which products go ahead, which go on the backburner, and which are cancelled, according to changing circumstances and better data. They would laugh at the idea of being told what to do by someone's chart from the past. That's not how you do business.
It's certainly not some kind of election promise, or a contract between a company and the rest of the world. They would never release one if that's how it was regarded.
It's always been that way. Jun Hirakawa was working on a 31mm f2.4 when the project was scuttled and the company went with other designers' FA 31mm f1.8 Limited, for example.