I have recently found out that the future of Qt has become uncertain as Nokia, It\'s current owner, has announced they officially have no interest in desktop Qt.
I know
I'm not sure if it's really a huge concern wondering if Qt will fall out of use. It is one the most (if not the most) popular cross platform libraries of its kind, and still has strong support.
Regardless, your question about other systems is still relevant. Here's my two favorites:
Switch to a cross platform language with standard support for what you need such as Java.
Script your app with a cross platform language with such standard libraries in order to build those parts of you app, while you still use C++ code for rest of the work.
They're pretty similar options, with the second being much less dramatic. Especially considering that the question was asked out of concerns for a library's survival, I would much rather bank on highly popular and mature languages to maintain support. Of course, there are probably many choices in language, but the one I'm most familiar with is Java, which is why I mentioned it earlier. It's not too bad writing Java code to interoperate with your C++ code, and is also provides a nice example of how using multiple languages in an app can be advantageous.