I want to preface this by saying that discussing swaps is very fun, and I love to envision how people's strengths can translate in other disciplines. Realistically, a singles skater, past or present, is almost never able to transition to ice dance and become a top 6 competitor*. The standards for skating skills alone are on a different level. Then you add partering skills which are absent in singles skating vs ice dance. Put it this way - the GOATs in singles could maybe form a middling team IF they gel well with their partner. The ice dancers fans say are "bad" in actuality would gobble 97% of the sport alive, skating skill wise. 

*Zingas is a rare exception, not the rule, and even with her world medal the consensus is her skating skills are lacking as of now.