A victory by the team seems 'within the realm of possibility'. [=a victory seems possible]
It's not 'beyond the realm of possibility' [=it's not impossible] that he will return.
new discoveries in the 'realm' of medicine
(..) You sure seemed like my enemy when you were killing my friends. For years the Night's Watch have sworn an oath to be the shield that guards the realms of men. And for years we've fallen short of that oath. You belong to the realms of men. All of you. (..)2015 TvShow: Game of Thrones Title: Kill the Boy Season: 5 Episode 5