Hard to say until we have the nominative list.
On the women's side, I believe Brazil, Canada and the US will take all the medals. The only exception could be on vault, where Alexa Moreno from Mexico has the potential to be a medalist. Maybe Cuba can be a surprise too, but they don't send their gymnasts to big competitions before the Pan Ams, so it's very hard to predict how they will perform.
On the men's side things are a lot more unpredictable. Jossimar Calvo (Colombia) and Manrique Larduet (Cuba) did not look too hot last year, and there's a chance they have not recovered their best form. The Dominican Republic, Brazil, United States, Mexico, Canada, Cuba, Venezuela, Puerto Rico, Chile and Argentina all have chances of earning medals. Even Peru and Uruguay have outside chances.
Canada's best chance of a gold medal is on the balance beam, or maybe all-around. Padurariu is looking great! On vault, it will be a tight battle between Canada, Brazil and the US for gold, with Alexa Moreno as a dark horse, though I don't believe she will win a medal if everybody hits, unless she upgrades one of her vaults. I'm very excited about what the Brazilians can achieve. I might be a bit too optimistic, but I would say that Rebeca Andrade will walk away with at least one gold medal. Last time a Brazilian girl got a gold medal was in 2007, and before that only in 1991.