Agreed, but a lot of people have been saying this for years. Sony has been shooting for December-March for its japanese games, and February-October for any other game. Sony has always been singleplayer focus though, and that is why they have dominated the space. A lot of Nintendo games were co-op friendly or taking turns and Microsoft has always been online multiplayer friendly. Sony games from the start with new ips like; Spyro the Dragon, Crash Bandicoot, Gran Turismo, LoD, Wild Arms, etc. excelled at Single player only and the PS4 and its SW was a return to form unlike the experimental stage with the PS3 and new ips like ; Resistance, killzone, MAG, Starhawk, LBP, Playstation All Stars Battle Royale, and etc.
I do think Sony should release a MH like game sequel to one of their Vita franchises during December-March for PS4, built from ground up.
3rd parties and 1st party alike have been ignoring the summer though sadly, I think some games can flourish during that time. Particularly an experimental MP game, maybe one that could potentially take off like Fortnite did.