Talking about Agile projects, release planning used to be discussed about just as frequently as sprint planning or sprint review, however; lately I have observed teams not really emphasizing much on release planning to make it feel like something non critical.
For starters, release planning was looked at a formal release at the end of x number of sprints where x could be anything between 2 to 6 sprints. However today, teams that are trying to derive classic benefits of Agile release their code more frequently than ever before. I have known of teams releasing code every sprint to teams that release code multiple times during the sprint. I came across a talk about continuous delivery at Etsy where the code is released in production 35+ times each day. This equates to a release less than every 15 minutes.
Speaking about teams that deliver that often, its quite certain that not much time is being spent planning for what needs to be delivered 2 to 3 sprints down the line. Planning happens in a “just in time” manner knowing the immediate needs of the customer.
Thinking through, it probably is time to redefine the term “release planning” itself to refer it as a method that allows customers to realize value on a continuous basis allowing for full customer involvement and speedy issue resolution or is it time to say “Goodbye release planning”?
Nirmaljeet's Blog 
CI/CD is the only way that can help us reach everyday releases but I still believe release planning plays a important role for teams to achieve the bigger objectives from business and platform perspective. ART does fall into it.
So what would be the name to replace release planning?