... would open London Heathrow to all US international airlines as well as to all European carriers wishing to fly between the US and London, subject to acquiring slots at the airport
and
...They would have to obtain slots and facilities to do so but the legal prohibitions that exist today would no longer exist
In other words, eveyone is more than welcome to fly to and from Heathrow if they can find the space and get the slots. Catch 22 springs to mind.