It looks like Insomniac still has some plans in store for Spider-Man, in a very "fantastic" form. In fact, that very word was used by a Marvel Comics representative, and during Fantastic Four Week no less. These facts combined make it pretty obvious that some sort of Fantastic Four-themed content is coming to Marvel's Spider-Man on PlayStation 4.
The announcement was made on a Marvel livestream meant to celebrate the start of Fantastic Four Week. Ryan Penagos, Marvel's VP of New Media, told viewers that "Something 'fantastic' is coming to Marvel's Spider-Man real soon. I can't tell you anything more right now...but you'll want to keep an eye out for this. It's going to be amazing and fantastic."
The announcement was repeated by the Marvel Games Twitter account, reports IGN, again emphasizing the word "fantastic." Insomniac Games, developers of Marvel's Spider-Man, responded with a simple emoji.
While that's not much to go on, fans have already been throwing out their theories in response. Most seem to agree that the teased content will be new suits, since the game's three-part story DLC has already been wrapped up. And since Spider-Man does have a longstanding friendship with the Fantastic Four in the comics, there are several suit options that fit the theme.
First is the Bombastic Bag-Man.
This silly getup came about because Spider-Man found himself without clothes after ripping off the Venom suit. The Fantastic Four had helped him dispose of the parasitic alien outfit, and lent him one of their own suits for his trip home. The problem was, the FF don't wear masks. As such, Spidey had to improvise by putting on a paper bag.
For a more serious suit, there's the Future Foundation.
This suit came about at the request of The Human Torch. When Torch gave his life in a heroic act, he asked Spidey to join the FF in his place. At the time, the family has re-branded as the Future Foundation, hence the switch to a black-and-white color scheme.
Finally, there is the simple Fantastic Spider-Man.
This suit was very short-lived, as Spidey never seems to get a long-term membership in the Fantastic Four. He wears it in several "What If?" comics where he leads the team, and briefly when he thinks he's joining the Fantastic Four in Human Torch's place. That assumption is quickly corrected, and he is given the Future Foundation costume instead.
Any of these three suits are likely candidates for a small easter egg download to celebrate Fantastic Four Week. Alternatively, Marvel could have been teasing a brand-new story DLC where PS4 Spidey teams up with the Fantastic Four. Although the planned story DLC is over, the game was wildly successful. There's no reason to think that Insomniac wouldn't return to the world it created and maybe even add a crossover. We already have Avengers Tower, after all.