PRINCE2 is unique as it focuses on the needs of the customer and is the perspective of the customers of a project.
The question it helps to answer is not so much HOW we will solve this problem or HOW we are going to build this machine or develop this application. It helps the customer focus on WHY we need it in the first place.+
It also helps customers consider WHAT is needed precisely to solve the problem they face and describe with precision what it is that they are prepared to pay for BEFORE going to a supplier and explain it to them.+
There is a Principle involved here which is "Focus on Products" which mean that a customer places a larger emphasis on WHAT is needed than on HOW it will be done.+
This also means that it is the result of an activity which matters most to the customer far beyond how long it will take to do that activity.+
Agile, Kanban, Lean-Startup, DevOps and other methods are focused on the delivery of the solution which is obviously essential and without which we would never have a product to serve the purpose of the project.
However these methods do not question why the project is needed and how much should be put aside to fund the project.
PRINCE2 has a different purpose and BOTH these set of approaches are needed in any project.
You need to identify, as precisely as possible, WHO will pay for the project, WHAT needs to be delivered and this is the function of PRINCE2. Then, in that order, you need to have a team who will do the work and deliver the products required by the customer who pays for the project and this is where Agile approaches play their role.
You need BOTH these perspectives to have a project, even if the customer and the "supplier" are part of the same organisation. In any project there is always someone who "pays" and someone who "delivers".+
More than ever projects need a clear direction, a clear path to follow even if the way they will ultimately deliver the outputs can be in an agile way.+
Agility does not mean no plan. On the contrary you need more planning (which can take the form of team boards) and more control from a project board to allow teams to develop the solution without the worry of dealing with problems that will naturally arise during projects.+
PRINCE2, as it is written today, is absolutely in line with agile behaviours.
PRINCE2 is agile by nature and distinguishes itself from other project management approaches by having integrated agility early on. It is true that PMI has now also integrated this idea which is stated in the latest version of the PMBoK.+
PRINCE2 has always been a precursor.
For example, it has been recommending the use of product planning way before others. It has now integrated the two perspectives of the customer and its suppliers with PRINCE2 Agile.+
Everything is PRINCE2 is flexible and anything can change at any time in a PRINCE2 project.
So, never forget this simple mantra : "Embrace Change"!