I'm worried that if they wait too long, many of the (talented) cast will have already moved on to bigger things. Chris Pine, Zoe Saldana and Anton Yelchin all have flaming hot careers right now (and are headlining movies; Anton Yelchin is starring in the new "Fright Night" remake this summer, and Pine is set to be the next Jack Ryan), not to mention Simon Pegg already HAD a big cult following before Star Trek.
I still think the writers made a mistake NOT banging out the next two movies right after the release of ST09, and shooting them back-to-back. Everyone would've been happy. But now the seemingly indifferent production team behind new ST would rather waste time writing/producing other movies/TV shows that they could've EASILY come back to after ST's 2 and 3 were done. At their current glacial pace of ST production, I'm beginning to doubt if we ever will see a third movie of this new series.
A shame... and a wasted opportunity.