History isn't helpful. Tornado sales efforts to Japan failed, Typhoon sales also look like a busted flush. The only success I can think of was the sale of a handful of HS125s for a maritime patrol role many years ago. Still, here's hoping...
Ultimately I expect the politics will come to the fore. Would anyone place a serious money bet against the USA coming out ahead?
The brexit complication for any future European collaborative efforts will be in the area of goods crossing borders (followed closely by people crossing the same).
EAP