You're absolutely right. It's entirely possible for SVB to sell their assets and cover the entirety of the deposits above FDIC limits.

Get real. The issue has never been that SVB's assets were completely worthless, it's that they're not going to cover all of the deposits over the FDIC limits. Ten year bonds were a bad idea and nobody wants them given the current interest rate trajectory. If SVB's assets could've been sold for their full cost they would've been. An assessment will happen, it's just a question of how large it will be.