I think if 10,000 seniors buy a console for themselves (not to give to their grandkids), then it's a success in the senior market. That's probably more than have bought any other console.
No, I don't have numbers to back this up, the 10,000 thing is pulled completely out of my ass. But the point is, when have consoles sold to senior citizens in any significant numbers? Anything measurable is a win.