I believe that Ancelotti will transform the team and bring out the best of them, because Brazil has great young players doing pretty good in their various clubs. I am happy that the Brazilian National team will be lively again.
Since Ancelotti never succeed with a national team, I'm not really sure that Ancelotti can instantly improve the performance of Brazilian team. But I believe Ancelotti has the ability to change Brazilian team, he has proven his ability by winning varied titles. Ancelotti is also very familiar with many Brazilian players. So, it will make it a bit easier to rebuild the team.
Brazil has no shortage of great star players and if you look at Ancelotti's style and ambition then I find a match. Where Ancelotti only needs his team filled with star-studded players, it might make it easier for Ancelotti to implement his game system. Once again the challenges in the National Team will be much greater and great players gather in one team, if Ancelotti fails his career is really over.