Technically speaking Ardor is not meant to be a transactional cryptocurrency - Ignis fulfills that role and NXT also did (kinda sad NXT price tanked so much). You can still spend Ardor if anyone is willing to accept it. I am expecting Ardor to remain a low transaction volume currency that will fulfill the job of a "reserve currency" for Ignis and other childchains.

Soon enough though you'll be able to sell your Ardor at exchanges.