Looks like they plan to have the blue line extension ready to go in 2029 mentioned in the embedded video not the article.
The plan is to have 55% of the population within 800 meters of public transportation stations by 2040.
A little bit old, but I always like to watch the video linked below: Youtube - Dubai Progress by MetroCucumber
UAE has done a good job transforming their country away from fossil fuels and I hope Saudi Arabia follows