No, conversion of "traditional" controller-based APs to Instant APs will never be allowed/supported. There are serious regulatory issues with enabling that.
However, for some time now, Aruba has been releasing "unified" APs, which support both controller-based and Instant deployments.
Those SKUs can be recognized as "AP-xxx-yy", where the traditional controller-based APs were "AP-xxx". The -yy suffix indicates the regulatory restrictions of the particular SKU, when used without a controller.
The current list of unified AP SKUs is: AP-203H-yy, AP-203R(P)-yy, AP-303H-yy, AP-303-yy, AP-34x-yy, AP-36x-yy, AP-318-yy and AP-37x-yy. All future AP models will be unified as well.
Hope that helps.