I stand by my guess (and its only a guess as we have had little indication).
Thanos will be doing his things and have all the remaining main stream Avengers on the ropes once again. It will look like another defeat. She will be fighting with them and also getting pummeled.
Then, like Thor tapping into his unknown deeper powers when Hela was about to finish him, she will tap into her Binary 'Cosmic powers'. Powers she did not know she had or could not control prior. that will force Thanos to retreat or buy the Avengers time to regroup and to eventually win. She will not get access to those powers again, that will be left for her to explore and figure out in future movies.
they have already indicated her CBU Captain Marvel character and Binary Character will be melded in the MCU so the question is do they bring her in, in her most powerful final form, or allow that to evolve out over time and a few movies. Given MCU history I think we see it come out over time. And we know the MCU wants to go more 'Cosmic' in the future so she will likely be a big part of that link.
I also think they are creating a very clear link for her to have some contact with the Guardians in the future, maybe as they tussle with Adam Warlock, known as 'HIM''. He will be released to bring the Guardians to justice by the Sovereign but eventually set his own path. He is a big lead into further exploration of both the Cosmic and Quantum realms.
And any potential battle between "Him" and "Her" could be a SJW financial bonanza
As long as they make sure "HER" wins over "HIM" as it should be.