Stop Being Comfortable
When things are working well, the temptation is to leave it alone and be consistent. Stable. Dependable. Those are admirable qualities, but go too long without change and you'll be left behind.
Remember Blockbuster? If not, Blockbuster was a physical store that you drove to, rented an actual VHS or DVD movie for five days (two for new releases), and then had to drive back and return it. I loved it as a kid, but my children would think that's an absurd idea. Why drive out and rent a physical DVD when you can click three times on Apple TV and stream it instantly?
Blockbuster was the de facto movie rental store. It did movie rentals really well, but come 2014 it wouldn't matter how well they rented DVDs, their business model had vanished.
Doing something, albeit extremely well, does not guarantee that thing will be relevant or valuable ten years from now. Resist stagnation, stop being comfortable because things "work," and find ways to innovate.