They haven't been attracting greater talent so far, not unless you mean the likes of Kaka, Rooney, and Pirlo. Meanwhile, LigaMX, which is far wealthier than some people realize, is the destination for some of the best young players from Argentina, Chile, and other Latin American countries.
And as for viewers, something else people don't realize is that LigaMX actually gets better tv ratings in the US than MLS does. In fact, even English-language channels like Fox Sports and ESPN have begun to broadcast LigaMX matches. So rather than MLS gaining traction in Mexico, it's LigaMX that has been growing in popularity north of the border.
Anyway, we'll see what transpires in the years to come.