30 years. I do wonder if that is true. Did they actually developed it under a time period of 30 years.
or do they mean it more in a way that it is a continuation of previous models.
It's more of a 'The concept is 30 years old' thing. Some of the reasons driving the commercial development only became factors in the market more recently; things like fuel efficiency and airport noise restrictions. Also, one of the less discussed advantages (as a customer) for the geared turbo fan is the decrease in expected maintenance/repair costs on the life of the engine. That's big business for engine manufacturers and there will be less of it with this design.
Did you read the article. I do wonder if that is true.