I think the potential of RubyMotion is in the "new ways of thinking and coding" aspect you mention -- the big potential win here is to import a Rubyish way of thinking about iOS programming.

I'm not part of either the ObjC or Ruby communities, but the impression I get as an outsider is that Ruby is a language and coding culture obsessed with elegant and minimalist expression, and ObjC doesn't make those things priorities. So what I'm hoping to see come out of RubyMotion is an obsessive drive to wrap the iOS frameworks in libraries that let you do the common things with no code at all, and the uncommon things with the least code possible. For people who have only worked in lower-level languages ... well, the difference over time could be surprising. At least I'm hoping so.

To put it in practical terms: I bet if you follow the sample RubyMotion apps over the next six months, you'll see the number of lines of code required to do what they do plummet, replaced by high-level libraries. If I'm right, let's get back together then and high-five. If not, oh well, it was a fun experiment.