I have 2 problems with your argument...

First, banks could never convince devs, miners, etc to devalue the worth of bitcoin. That would be financial suicide for the bitcoin infrastructure.

Secondly, why even choose that route when all banks have to do is keep forcing financial regulators to give more onerous and stifling regulations on bitcoin exchanges and merchants? That's already having major effect on bitcoins acceptance, and is co-opting it's original intent of decentralization and anonymity.