Three opinions on this and Allah knows best. No doubt its origins are kufr and totally Haraam. Some say Haraam full stop, some say permissible, some say permissible after certain conditions are met. To come out of the difference of opinion my personal opinion is stay away from it completely and do other exercises.
Lots of Muslim women suffering from diseases like cancer, weight problems, body dysfunctions are regularly given yoga classes or recommended to practice here in North America. They are informed that it promotes a healthy living. And talking to the women, i found the overwhelming majority agree wholeheartedly. Its a norm like coffee with nearly all gym clubs, physical therapy centres, and hospitals having workshops, and most of the times the instructors are indian hindus.