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
I have only recently gone to Dubai Creek and the traffic in and out of there was really bad. I think they are targeting the highest chance of ridership first. I think the people going towards Sharjah is probably going to be the most numerous.
Personally I am more interested in the parallel line to Al Maktuom Airport, but I guess the ridership will be too little now.