Pretty confident that Crash is going to be one of the E3 reveals this year because Nintendo is very deliberate in which characters they show at E3, especially if they're third party. They knew exactly what they were doing with Megaman and Pac-Man in Smash 4. The significance of them being revealed at E3 is largely self explanatory:
Megaman- Three year hiatus from gaming and Capcom absolutely loathed Inafune at the time. Seemed to deliberately nuke anything that Inafune had been actively involved with and cancelled multiple major Megaman projects. Megaman at E3 2013 was definitely a statement about not only Smash but Megaman's future too.
Pac-Man- A lot of people were concerned that Pac-Man was going to have his Ghostly Adventures look but thankfully Sakurai went with his classic look. Even if he wasn't the most wanted third party character, there's no denying he's a global icon and absolutely deserved his private showing.
Ryu- Once again, not the most wanted third party character but Mr. Fighting Games himself. This is why Ryu getting added was honestly a bigger deal overall than Cloud. Ryu is a crossover king, probably second only to Mario. Once again, absolutely deserving of an E3 reveal.
Hero- Dragon Quest is a big deal. Not only did it basically set in place most of the major tropes for JRPGs but it's a juggernaut in Japan. Beyond that, the series is kind of a liscensing nightmare and for Sakurai to work out a deal to include it in Smash is nothing short of a miracle.
Banjo- Similar story to Megaman. Big fan favorite, especially among Nintendo fans, that had been gone a long and worrying hiatus with multiple major projects canned, only to appear in Smash.
Crash is yet another character similar to Megaman and Banjo. Absolutely beloved character but fell from grace, took an almost decade long hiatus only to come back thanks to amazing remasters. Now the table is set for Crash to make a true comeback as a gaming star and what better way to celebrate that than Smash? Not a huge Crash fan personally but Crash deserves nothing less than an E3 or VGA reveal.