I think Steve would have to try to change the bad things he knew were going to happen, no way he would just sit around twiddling his thumbs. He'd save Bucky, try to save Howard and Maria, be instrumental in making sure Hydra didn't infiltrate SHIELD. It still doesn't answer the question of the new timeline's Steve, does he stay in the ice to one day wake up and realize another led his life? That's my biggest problem (in a story full of them) with the way Steve's story went down. In my mind he rescued him too, and helped him to know about the things that were coming and then left to help out somewhere else he was needed. That's the only way I can still love Steve.
I do feel like Steve's ending wasn't given the same thought as Tony's. Tony's story made sense to me and did not leave me with that WTF feeling at the end. Whereas with Steve it's like, how can we get him off the board, and it just seems sloppy to me.