Assume they won't, and then you can be pleasantly surprised if (a) they do and (b) you get targeted for it.

(My guess, and it's just a guess: no, it won't be run again. I suspect it was an attempt to draw people back to higher-value SkyMiles Amex cards and/or to increase their spending after the change in the Diamond Medallion waiver, which convinced me to drop the Reserve down to just a Platinum.)