As a technologist your career will be filled with change. New technology, new versions, new platforms, and new approaches are a constant in your chosen field. Often times skills are referred to as tools in a toolbox. For you these tools are more like arrows in a quiver. Many times you can use them over and over but eventually you are going to need to replenish your supply or you will eventually become less effective or worse, irrelevant.
You simply cannot rely on just becoming better at a single skill. You have to be on the look out for new, hopefully complimentary, skills to learn. You have to look for new arrows to add to your quiver. This is what will keep you relevant and make you more valuable to your organization.
Don't be satisfied with what you are capable of today. Don't be satisfied with what you will be capable of tomorrow. Be satisfied that you've committed yourself to constant learning and growth. Be satisfied that you won't stop learning new skills or adding arrows to your quiver at any stage in your career. Be satisfied that you refuse to become irrelevant and that you will always add value to your organization.
Your quiver is never full. It is up to you to find ways to refill and redefine it.
Get out there and conquer the world.