We're lucky there is a chance for him, or any character, for that matter, to get in at all.
Looking at the surprisingly high number of vocal Isaac supporters all over the internet, I'm pretty confident we have a good shot of getting thisadept the Mac treatment he deserves.
Also, if we actually are, just an example here, to get 5 characters + Wolf, it would still be an absolutely mindblowing amount of characters to be added to a full game like this.
We have it in our own hands, people. We don't have to hope for anyone over at Nintendo to have a sudden flash of insight anymore. It's up to how many people vote for him. And, honestly, seeing how many people have voiced their support over the last couple of days, I'd at least say Isaac is one of the more likely characters to be considered.
I'd say chances are we're going to see one character + Wolf at E3. Just a quick tease or announcement, kinda like Mewtwo. They'll hardly be sitting on their behinds all day moping over at the Smash dev labs.