I have a few specific expectations for E3. For one, I think the official packaging for the starter pack and figures will be released, as well as the release date as pre-ordering should open up shortly after.
We should also get a bit more confirmation on the different ways that they will offer the 2.0 upgrade apart from the starter pack already announced, like a digital download or a base owner pack.
As for figures, we should definitely get to see the figures for Merida and Maleficent, and not just the concept art. I assume that Nick Fury and Stitch will be confirmed as a playable character, as well as the Guardians of the Galaxy playset and characters. If the current rumour of Thanos being playable is true, I feel like he won't be confirmed until SDCC considering Marvel hasn't even said who is playing him in Guardians of the Galaxy yet.
Anyway, those are my main expectations for E3.