you need to think 2nd order effects: VCs need mega exits to make returns, which usually are blockbuster IPOs. Higher rates will crash quite a lot of high-growth stocks making IPOs less appealing for investors, which messes up with A16z business model of exiting via IPOs.
They can also get fabulous deals currently so it is not bleak as it sounds. Also both Andreessen and Horowitz have that cockroach like ability to survive so I would not count them out even whole business model would collapse overnight.
