I'm starting to worry about London's status as a global business and transport hub.
This is going to affect LHR in the future, especially if coupled with potential ESTA-like visas to be imposed on visiting (or transferring!) passengers. Add the incredibly stupid decision of having HS2 passing within 20 km of LHR without stopping and the uncertain times for UK trade in services with the continent... it'll really dampen London's competitiveness.