Patience is a virtue. The best way to estimate when Virtual Villagers 3 will be out is to look at how long it took between 1 and 2. The time between 2 and 3 will probably be shorter, since when they did 1 they had to wait and see if it was a success.

In order to figure out improvement to include in version 3, they need feedback, which takes time... these are all factors.

Above all just hold your horses and enjoy what you have...