^ I hope so as well. If she does return to form -- as in, running sub-50 & being in the 2015 WC final and/or the 2016 OG final -- it would be a great story. Just to come back to sub-50 would in itself be a great story. A quick scan of the all-time 400m list shows (assuming I counted right) 75 women who have run sub-50. Hardly any of them ran that fast at age 30 or older. Kratochvilova is the prominent example, but behind her on the all-time list, there are few others to have run so fast so "old." In a quick scan of the records of these 75, I counted just 8 who broke 50, at age 30 or older. So, it can be done, but it is rare.
Pego's note about the effects on bone density of corticosteroids is pertinent, I think. Moreover, there is simply the duration of the career and the effects of the training stress: SRR has been competing on the national level, starting with Youth/Jr/etc., since 1999 -- inclusive of this year, that's 15 seasons. Internationally, she has competed in some championship event (WJC, WC, WIC, OG, WAF, World Cup) every year from 2002 through 2012 (except 2010). That is a lot of 200s & 400s, a lot of high intensity work.
I would love to see her come back. She is a favorite, and, imo a great representative of the sport. But this is also how the ends of careers begin -- a surgery or an injury doesn't heal quite right or quite fast enough, etc. But I am hoping she does come back.