“No more folders full of printouts of reservations and bookings.”
I don’t wish to sound like a Luddite here, but the problem is whenever I arrive at the Immigration counters the first thing they ask for are print outs of your itinerary. I used to have the travel booking electronically, but now its quicker and easier to carry print outs.
Especially in countries where English is not their first language, a print out of your ticket is far easier than trying to explain with an iPhone. I expect it may take some time before Immigration catch up on this front.
I am not sure what you mean by:
“automatically updates new aspects of the journey.”
Surely if your flights change the airlines would notify you of the changes, I don’t believe it’s the case that they shift around the timings, just like that, unless it’s just a charter flight. Trains & boats are much the same except trains don’t notify of changes very well.