Rat 5
If you lose separation with traffic within a few thousand feet then realistically there's nothing we could have done as by the time we get the avoiding action out of our mouth you have probably already descended through their level.
Which is why, IMHO, TA Only ASAP is more important than 7700.
So you are over the center of the UK at FL380 over exceptionally busy climbing and descending traffic in and out of London metroplex, having left the Atlantic east bound to Paris and you get an explosive decompression. You would seriously go to the 3000 ft transition altitude just barreling on down and hope everyone will do something? I assure you that if you spend a couple of seconds setting 7700 everyone will be far safer. Traffic below you in your path 50 - 60 miles ahead will be turned away without any coordination necessary.
If you look at my initial response I said you should look at TCAS and avoid any traffic in your immediate vicinity. In areas of busy and complex routes turning 30 right and other such rules of thumb will not work, just aim for what TCAS tells you is a more empty area and 7700. People will then move out of your way.