Indeed, USDA recently published new proposed rules requiring meat processors to properly label mechanically tenderized meat products. In addition to requiring processors to label these products as “mechanically tenderized,” USDA also will require processors to include validated cooking instructions which, if followed, will ensure that any harmful pathogens in these products are destroyed.
The question for industry will be whether cooking mechanically tenderized steaks to the higher temperatures needed to kill foodborne pathogens will prevent them, in most cases, from being served “rare” or “medium-rare.”
To justify its new rules, USDA cites a number of recent outbreaks caused by the consumption of undercooked mechanically tenderized steak. According to USDA, since the year 2000, there have been a total of six E. coli O157:H7 foodborne illness outbreaks attributable to mechanically tenderized steaks served in restaurants and consumer homes. These six outbreaks, spanning 13 years, have included a total of 176 confirmed E. coli O157:H7 cases that resulted in 32 hospitalizations and four cases of HUS (acute renal failure).
While I let you decide for yourself whether such a substantial labeling change is warranted by the fewer than 15 cases reported annually since 2000, what we do know is that the labeling rules are about to change, and serving mechanically tenderized, medium-rare steaks in restaurants may no longer be an option.
Time (and temperature) will tell. Ultimately, it will depend upon the validation studies governing any new labeling. The USDA’s rules will require validated instructions to include, at a minimum: (1) the method of cooking; (2) a minimum internal temperature validated to ensure that potential pathogens are destroyed throughout the product; (3) whether the product needs to be held for a specified time at that temperature before consumption; and (4) an instruction that the internal temperature should be measured by the use of a thermometer. 
In turn, processors will need to demonstrate to USDA that the instructions are also “scientifically supported,” meaning they must demonstrate that: (a) the cooking instructions can repeatedly achieve the desired minimum internal temperature and, if applicable, rest time; and (b) the minimum internal temperature and, if applicable, rest time achieved by the instructions will ensure that the product is fully cooked to a level designed to destroy any potential pathogens throughout the product.
So, if you like selling or serving (or, I suppose, eating) steaks that can be cooked to medium-rare, you may want to watch the development of these new rules closely. 
In the end, “medium-rare” may become much more rare you think.