Ancelotti emotional closeness with several Brazilian players will certainly speed up his adaptation period, I don't think Ancelotti will experience any significant difficulties. The World Cup qualifying round will be a good event to build chemistry, we will see clearly how Ancelotti performs at the national team level. I think all managers will still need time to improve the team performance, especially to bring Brazil back to its glory days. But at a glance, I think Ancelotti has the ability to do it, he is in the right place and the right time.
We cannot certainly say that Carlo Ancelotti will not face any significant challenge in the Brazilian National team. Yeah, a few key players might be his former players, but there is still a whole lot to deal with. My biggest fear is the politicization of the national team. I read that some members of the Brazilian Football Confederation are engaging in politics. And this had really affected the administration of the national team. Ancelotti would enjoy his stay in Brazil if he is given full control of the national team.