Relying on Others...
Surely the recent Syrian example has shown how reliance on other nations may not always deliver the capabilities you have assumed. Admittedly the example is the other way round (i.e. we didn't play when the US wanted to), but I think it highlights the limitations of that planning assumption when national and political self-interest come into play.
Clearly we retain a level of national ambition and capability that doesn't rely on the assistance of partner nations, but I suspect that is actually a very thin veneer when actually tested. It's time to start being honest about our limitations.