I would love to see (And the fact that it's actually possible adds a certain...lubrication...to this dream) a Star Wars/Transformers crossover line. With Autobots as Alliance ships (X-, Y-, B-, A-Wings, Snowspeeder, and the Falcon as the leader) and Decepticons as Imperial craft (TIE, TIE-in, Bomber, Vader's Tie, an AT-ST, and an AT-AT). All Action Fleet scale, but to-scale.
That would be the initial releases, more could follow (Landspeeders, Cloud Cars, Shuttles, Speeder Bikes, maybe even prequel ships with a "prequel" storyline). Just as long as they were "classic" style TFs, ie they were mostly one piece with an "authentic" looking vehicle mode.
Throw in a few Action Fleet- styled SW heroes and villains (Or can you imagine Han, Luke, Chewie, Vader etc. as Headmasters and Targetmasters?)
Unicron as the Death Star, anyone?