Duplicate citation cleanup—not just “suppression”—is probably the main citation-related tactic that I’d continue to pay a substantial sum for. Otherwise, just manage your listings directly in Google My Business and Facebook, and if you can afford the cost and the sales headache, Yelp. Then call it a day and spend your SEO budget on more productive tactics (like review solicitation, Q&A monitoring, and the like).
Beyond Yelp and Facebook, Google seems to be moving more and more towards valuing vertical and local sources, most of which aren’t part of standard listing networks. Companies like Yext and even my own former employer Moz, will probably need to adjust their business models and value propositions accordingly.