No, this really is not possible. The backup of a rule reflects the internals of the app (e.g., Rule-4.1). Under the covers, Rule 5.0 has been rewritten in many areas to make it more efficient. So while it looks mostly like Rule-4.1 on the outside, it actually is very different on the inside. An attempt to map from 4.1 to 5.0 would be a difficult to impossible task, a huge undertaking. So, that's not going to happen.
Having said that, there is no reason to move an existing working rule from 4.0/4,1 to 5.0. If it isn't broken, don't fix it! If you want to change the rule to use new features, make a new rule. I still have working rules from all prior versions of Rule, dating back 4 years. Once in a while I'll look at an old one, and once in a while I'll redo it -- but they work, so there is no need to do anything.
