Ever since Harry Potter and the Deathly Hallows, the last installment of a franchise is a fungible concept.  Sure, you could conclude your story in a single movie, but why not draw out the good-bye a little longer?  We've seen it done with Twilight, The Hunger Games, Divergent, and now it might happen with Earth's Mightiest Heroes.  According to The Daily Marvelite, the final battle against Thanos is too big for just one movie.  This rumor is supported by Marvel's recent and mysterious release calendar which allows fans to plug in wishful thinking with regards to the dates.  A few months ago, Marvel announced a slew of dates for untitled pictures.  One of these dates was May 3, 2019, which we initially assumed would belong to The Avengers 3, but then a week later, Marvel also announced a movie for a May 3, 2018 release date.  A source tells the The Daily Marvelite that the date was added because The Avengers 3 is spread across two movies.Hit the jump for more, and how The Guardians of the Galaxy might crossover into the culmination of the Avengers 3.guardians-of-the-galaxy-imageThe Daily Marvelite reports that they're not sure if The Avengers 3 will be two-part movie, or if it's a single story split into two parts where The Avengers handle the first part, and the second part will be a massive crossover involving The Guardians of the Galaxy.  This speculation would tie into Vin Diesel's comments about "merging of brands":

I get the call, I go down to Marvel. A great meeting. It was even talking about something so big I can’t even talk about because it’s like the merging of brands in a way, which I won’t get into. That was something way, way, way, way, way down the road.

This could also just be Vin Diesel being Vin Diesel.  Ask him how the next xXx is coming along.

However, a two-part movie bringing in Marvel's highly popular teams doesn't seem completely out of the realm of possibility.  But if that's the case, then Thanos really needs to step up his game when it comes to collecting Infinity Stones.