Also, Marvel should save Avengers 3 for 2019. Mostly so Carol Danvers and T'Challa can get their own films instead of being pushed back to Phase 4 or 5. IMO, Phase 3 will be dissapointing if it's just
Ant-Man, Captain America, Doctor Strange, Thor, Guardians, Inhumans, Infinity Gauntlet
Then I'd throw a fit. Mostly since I've never cared for the Inhumans at all in any way when there are properties that I do like that Marvel are ignoring.
IMO, it needs to be
2015 - Ant-Man
2016 - Captain America: Civil War, Doctor Strange
2017: Thor 3, Guardians 2, Captain Marvel
2018: Hulk 2, Black Panther, Inhumans
2019: Avengers: Infinity
Give the MCU another three films, let Hulk have another solo film to introduce She-Hulk and finally follow up on The Leader, introduce two more heroes and then bring the Inhumans in. That also allows more time to negotiate for Spider-Man back since he can be done on TV, allows She-Hulk to also get her own TV show and allows Avengers 3 to be the biggest, most epic film of all time. Moreover, if Fantastic Four flops, it means that Marvel also has time to buy them back from Fox and reintroduce them in Phase 4 and can stretch out TV plans with Runaways, Moon Knight and Punisher. I'd introduce the Eternals in Guardians 2 and just state that Drax is one of them.
This would mean that Thanos wouldn't just be fighting a handful of heroes on Earth, he'd be fighting against every character that Marvel owns except for Namor, Ghost Rider, Blade and possibly the Fantastic Four. That's still one big, massive army for Thanos to contend with and the best possible reason for stretching out Phase 3 there is.