This hardly seems like news to me. You'd hear the same from any film-series director this early in the process. We heard the same from Abrams about his second Star Trek
movie, from Peter Jackson about The Hobbit
, etc. Directing a movie is a huge investment of time and effort, and surely a director as successful as Whedon is right now is getting plenty of other offers that he needs to weigh against doing Avengers 2
. So it's natural that he'd take his time before deciding.
The only really important element I thought Whedon brought to the party was his dialogue/banter , which for me really made the film (quim, anyone?). The action was pretty perfunctory (if entertaining), and isn't most of that stuff done by second unit/stunt directors anyway?
The second-unit directors and stunt choreographers, like everyone else, answer to
the director. He approves or rejects all their suggestions and their job is to enact his decisions. Everything you see onscreen in a feature film has the director's stamp on it.
I think Whedon is a superb action director, particularly in Serenity
, where he had the good judgment to rely on long master takes and let Summer Glau and the other stunt performers really show off their skill, rather than hacking everything into second-long cuts like most filmmakers these days. There wasn't as much of that in Avengers
, due to the much greater VFX demands, but you could see his trademark in that elaborate "master shot" that tracked from one Avenger to the next to the next without any visible cuts, like a CGI/action equivalent of the opening-titles sequence in Serenity