Well, with a writer's strike going on scripts are going to be a little long in coming. Then you have to coordinate the talent's schedules and the director and producer.... etc. Then actual production and post production could take as much as a year. 6 years might be realistic... but sad.
George Lucas is a billionaire. Most people who want to be writers are not. He basicly mortgaged his underwear and everything else he owned to finance Star Wars and if you recall that paid him back times like a billion. If someone else thinks they can do it, then yes, go ahead and cross the picket line. But they are risking their careers if they can't.
Here's director Gore's Verbinski on Pirates 4 in an interview:
Q: Are you planning on doing a 4th part?
A: I think the trilogy is now complete. All of the stories set in motion by the first film have been resolved. If there ever were another Pirates of the Caribbean film, I would start fresh and focus on the further adventures of Captain Jack Sparrow.
Well, that's a relief. Unless Disney decides they don't care what he wants and that he can either direct the movie they want to make or they'll find another director. I kind of hope they don't do that though. I've really enjoyed Verbinski's vision for these movies.
But the ending of PotC 3 is definately left open... we can agree, it's an obvious "attempt" to lead you into believing it will continue.
Heck yes it did. There is a wealth of material to pick up and move on from. They never have to touch an old story line if they don't want to. Honestly if it can be done without Elizabeth I'd even prefer it that way.