Thanks. I sent them a note and they replied quickly. They said there were no plans but that they would forward my note to their marketing department. For the type of shooting I do, the absence of a ~6.5"+ barrel keeps me from buying a Single Ten.Ruger.com has a tell the CEO link where you can submit your suggestions. Tell him. If they hear it enough, you'll get your wish.
Anything is possible. The Single Ten is just another variant in their long-running Single Six line that's had more variants than anybody could possibly count.
I'm tending to suspect 6.5 & 7.5" barrels are not a high priority, given that the SA .22 revolver market is already a tiny niche (which is already dominated by Ruger).