Ticket sales for the NIN Mexico City have been delayed until further notice. From what I can gather, it's either to do with lack of communication between the band and the venue and Ticketmaster, or something to do with confusion about ticket prices due to confusion about the way the venue is laid out. CIE, the promotions company are alleging that it's down to the band not confirming the date yet. Chances are, the tickets may not go onsale for another week.
(Co-incidentally, the sale date for tickets - but not the actual concert date itself - has now been removed from the performance page
A sincere thankyou to Enrique and Emmanuel for providing the information again.