It's not as simple as saying 'the Americans turn up every year but never fly'. They have set demo teams and the crews from those teams have to be temporarily re-located from the US to Europe, whereupon they fly European-based aircraft. So last year's A-10 demo at RIAT, for example, was flown by the standard demo crew but in a jet drawn from the A-10 units at Spangdahlem in Germany.
Anyway this is all rather moot, since there is no chance of an American fast-jet demo in 2012. They have drastically cut the number of fast-jet demos, indeed I think the F-22 is the only one left on the circuit, and they have pretty much confirmed that it won't be doing anything outside of CONUS this year. Not even the mighty RIAT will see a US fast-jet demo this year, other than perhaps the Boeing F/A-18E/F Super-Hornet demo, however note that it is provided by Boeing themselves as opposed to the US military. And it'll only be there because of the coincidence with F'boro.
Leuchars's clash with Saniciole is NOT good news, since it has a large pull as an airshow and also has an established reputation for attracting foreign (i.e. other European air arms) participation. The only thing which might help is that they don't actually have a show on the Saturday - Friday evening and Sunday are their dates - which might, just might, allow assets to transit over to Leuchars from Kleine Brogel (which is where Sanicole's flying participants are based for the duration of the show) on the Saturday. However, with all air arms keeping one eye on the budget, such complex and potentially costly transits between shows are likely to be viewed in a dim light.
Perhaps Leuchars could explore one of the less common F-16 routines, from either Norway, Denmark or Turkey. Would potentially be more interesting than the Dutch and Belgian displays which, although brilliant, do suffer slightly from over-familiarity.
Posting comments on an aviation-related chatroom, are ya? Looks like it an' all...