When Robin Peterson is part of the "best attack in the world", it provides a little bit of context. Is spin bowling really the issue at hand?
I really think the incumbents are being underrated here. Ojha is good. Sure, he's no Herath or Ajmal, but he'd walk into most non subcontinent sides. As for Ashwin, he's a handy second spinner. You wouldn't pick him as first choice, but he offers good variation and will develop consistency. Put them behind Umesh Yadav and some of the promising young fast bowlers (I really like the look of B Kumar) and they'll be far more effective.