No, MailChimp's conditional merge tags don't support wildcards inside of those merge tags.
If the end goal is to show X content to subscribers who have no group affiliations and show Y content to subscribers who have any group affiliations, there are a few ways to accomplish this.
a) You can use *|INTERESTED:GroupTitle:GroupName1,GroupName2,GroupName3|*, etc. to show content to any members of those 3 groups. If you have more than that, of course, just add all of your groups in there with that comma-seperated format. Then, use the *|ELSE:|* as you already are in your example to account for people who aren't tied to any of those groups. This can be tedious though if you have a ton of groups.
b) Consider sending two separate campaigns, each set to send to a segment of your list that targets based on group affiliations (or non-affiliations).
sources:
http://kb.mailchimp.com/article/how-do-i-use-smart-merge-tags-with-groups/ http://kb.mailchimp.com/article/how-can-i-send-to-a-segment-of-my-list/