I don't think Gammora is staying dead, like you said, likely tied to the soul stone, plus the 3 GOTG movies need to be coherent with each other, you couldn't suddenly have her alive in GOTG 3 when she's dead in the universe, or all of a sudden she's dead in GOTG 3 with no explanation between that and GOTG 2.
The only characters that I think have actually died are Loki, Heimdall and Vision. The other "real" deaths will come in Avengers 4, seems intriguing the people who are left after the snap are basically the original Avengers, being those who are more likely to duck out after Avengers 4, thus it'll likely be a swap, people who were dusted before will come back with the power of the gauntlet, but will die in the process, save for a few such as Hulk. Strange knew Stark had to live to have a chance in beating Thanos, so it seems likely Stark will die in Avengers 4 as a sacrifice to save everyone, it also goes along with him making Spiderman a part of the avengers in this film, to pass the baton to the new avengers after Avengers 4.