Forgive my meddling in this one, but I confess to being a little wary of this notion.
I rather like that Cypher is very graph focussed, and addresses the domain of the database. If we choose to add in functionality like this, Cypher becomes more and more like a general-purpose programming language. I don't think that's helpful because:
1. We know it's not a good idea to encode business logic in queries..
2. There are lots of good programming languages out there already which can easily handle the return val = "DELHI" ? 5 : 10 case. Note that neither 5 nor 10 are actually about data access and manipulation here, they're domain things.
Even if those features existed in Cypher today, I don't think in good conscience I would use them to develop a business information system - I think it conflates concerns.
Just my £0.02.