Microsoft has not announced that they're working on Silverlight 6. And some people have asked me what I'm going to do about Regex Hero when Microsoft drops support for Silverlight. Well, there are certainly options and the options are always changing and evolving as new technologies are introduced.
However, we do know that Microsoft has announced that they will support Silverlight 5 until October 12th, 2021. In the meantime we'll likely see more and more attractive alternatives. And there's still the possibility that Microsoft will build a Silverlight 6 and extend the support for it even further. All said, the decision about Regex Hero's future codebase doesn't really have to be made today and we don't have to panic since we have at least another 8 years of Silverlight.