Now you may run android apps on windows 10 phones. According to market most of the people whether they are smartphone user or a smart phone expert, think that the biggest drawback of the windows phone is, that you cannot run an android application on windows platform.
Now may be Microsoft is planning to make windows 10 OS phone android friendly. So now you may run an android application on your windows 10 smart phone. The project is still on hold but as for information Microsoft is testing the concept internally.
It was an obvious thing for Microsoft to think of this step because windows phone are not getting that much response like Android phones are, in this market. Meanwhile Microsoft was also planning to move to android phone instead of windows phone.