It seems to be related to a change from Google to the Android SDK.
Cf: http://tools.android.com/recent/androidsdktoolsrevision2530feb2017
"Obsolete/deprecated tools have been removed: […] Project and activity templates"
I guess we have to wait for a fix from the Ionic team 
(I’ve filled a bug report: https://github.com/driftyco/ionic/issues/10604)