1. Even though it's still referred to as a 'frequent-flyer program', SkyMiles rewards people via a combination of flying and giving revenue to DL via other channels.

DL only used to allow one MQM bump per year from the DL Plat card (excluding sign-up bonus), but several years ago they started allowing two because they noticed that people stopped spending on their DL Amex after reaching the threshold for what is now bump #1. Whether you like it or not, given that DL went that direction in the not-too-distant past, I highly doubt status earned in part (or entirely) via Amex MQMs will start to be treated differently from pure-BIS status in the future.

2. How about rollover? On my last flight, I overheard a guy talking about how due to rollover and frequent trips to Asia, he was guaranteed DM status through 2014 (not sure if he meant expiring in early 2014 or through the 2014 program year that ends in early 2015). What if he stopped flying today? Although his status was technically BIS-based, if we fast forward to 2013, should the fact that his BHBIAS (butt hasn't been in a seat) in over a year still allow him to have DM status?