Both carriers have not operated DC-10's for 5 years now. Quite some time ago. Although such a type would benefit Mexicana for their Mexico-Cancun-Buenos Aires service currently flown by a 757. However, I really think that even though they want to return to widebodies they don't want to operate another type of
aircraft just for one route.
It is currently believed that the 727s A320s and F-100 will be replaced by 737NG not more A320's.
AeroMexico would be more keen to operate such a type if their load factors to Europe continue to grow, but at this time the 5 767's are profitable enough to fly daily to Paris and Madrid.
Both AeroMexico and Mexicana are not doing bad at all. As a matter of fact they are the two most profitable air carriers in Latin America. However, this was not the case 6 years ago when AeroMexico purchased Mexicana. Both carriers almost went bankrupt. I think you're refering to this time.
Click for large version
Photo © Thomas D. Mayes, Jr.
San Juan, Costa Rica/ Alajuela-Juan Santa Maria International airport.
Pan Am - The World's Most Experienced Airline.