LOS ANGELES—According to insider sources, the future of HBO’s Game Of Thrones is currently in doubt, with the hit fantasy series facing a dire shortage of weather-beaten, bedraggled old men to cast. “A lot of the big crowd scenes in season two really depleted the available pool of greasy-haired bearded actors over 70, and for the sake of continuity we can’t really reuse them,” executive producer D.B. Weiss said Monday, stressing the importance of having a minimum of one new elderly and disheveled male character in every episode of the epic drama. “I honestly don’t know what we’re going to do. In the third season, we have at least a dozen war room meetings to film, and you can’t shoot a war room meeting without having at least two or three poorly groomed old guys with big, tangly beards hanging around.” The Game Of Thrones crisis is the latest in a series of casting woes to beleaguer HBO, which in March announced it had already used up its annual allocation of Steve Buscemi.