However, despite Eurocontrol being more states than just the EU, the EU commission has the voting rights of all EU states, being able to overpower any other vote on that gremium, and even more importantly, the EU single sky is not an Eurocontrol agreement, it is an EU treaty, same as the EU open skies agreement with the USA. And while the EFTA will lose traffic rights into the UK in case of no deal, the UK will lose traffic rights into the whole EFTA, which is quite a bit more market than the other way round, not to mention all traffic rights into the USA and other states where the EU negotiated agreements will be lost as well and will have to be renegotiated. Of course the Montreal Convention still stands, so overflying the UK, including Shanwick, is still possible, just not landing dependent on commercial agreements.
Interesting to see the UK once again trying to circumnavigate the EU commissikn, however, any new air traffic agreement can only be negotiated by the EU, not by single states anymore as the UK should know very well, that happened after all on their initiative, as so many other things did in the EU.