@FlightlessParrot:
I'm no fan of MS*, but one thing they have always done well is making life relatively stress-free for developers. As long as Delta's in-house software was written either in a CLR-compatible language (e.g.
VB.NET, C#), or even in C++ as long as the APIs are strictly adhered to, then cross-compiling to the ARM platform is trivial.
[* - or Apple for that matter!]