Why not? It is an interesting theory, is it not? Your stories tend to have happy endings, so why would The Box be any different. Besides, people DO fake their own deaths, so it's not like it's totally unheard of. Rather it's an unlikely, but so is being in the midst of uprisings and/or riots in the US, France, and Russia (all three within one's lifetime). Oh, and I suppose that they'll be in the midst of the 9/11 attacks in the next story, no? See? All of these things are unlikely, so we should expect something unusual like people faking their own deaths. And didn't Tonto say she was hiding his secrets? What bigger secret than the one that Steve and Aaron are actually alive, albeit very old and likely to croak soon.