Hybrids between 2 different genera (known as intergeneric hybrids) in the same family are possible, and are actually quite common in the Orchid family. However, this has never (as far as I know) yet been achieved between 2 different CP genera. Sundews (Drosera) and VFTs (Dionaea) are both within the Sundew Family (Droseraceae), so they are fairly closely related and an intergeneric hybrid (let's call it x Dionera for reference!) could in theory just be possible - however it is very unlikely to happen, and even if viable seed were produced and germinated, the seedlings would likely not live very long. However, it would be an interesting experiment, and there have been rumours in the CP community that some growers have succeeded (albeit temporarily) in creating such a hybrid - but these are probably just rumours / urban legends! Go ahead and try anyway! It's an interesting experiment, and if a hybrid were ever produced and documented, it would help determine that Drosera and Dionaea really are closely related (some CPers, e.g. Don Schnell, dispute this). Just don't expect anything exciting to happen though (one in a million chance maybe!).
(Supposedly the Sundew that is closest related to the VFT is Drosera regia, so that might be a good hybrid to try sometime!).