Small changes would happen yes but nothing too major like what we see with the different variations of Ben 10,000. Like I mentioned that Fusion-MX started distancing himself from his family to focus on his hero career but that could be one aspect that is subject to change after he and his younger self met each other. Like, I doubt Nicholas would make the same mistake after seeing his future self do it. So yeah, small changes would happen to Fusion-X’s future self and the world of the future but nothing to drastically different.