If your console is connected to the internet you should now (or very soon) be able to download the final update to Disney Infinity 3.0 that brings in the Finding Dory Play Set which is due to launch in about a month's time - so if you see the Play Set in the shops early and are able to buy it you'll be able to play right away.
The update also heralds the arrival of ten new Achievements and Trophies for Marvel Battlegrounds and the Finding Dory Play Set as well as five pages of new Finding Dory themed items for your Toy Box.
So far it doesn't seem that the patch has accidentally left in any hints to any of the other originally planned characters but in case you missed it Kotaku posted an article last week detailing some of the plans that were in place before the game got canned. It includes things like the identity of the Disney Animation Play Set (Moana, of course), a range of giant sized premium figures, and even some of what could have been for 4.0.
Alice, Mad Hatter, and Time are due out next week. And the Finding Dory Play Set and Nemo are due out in a month to round out the series.