Unbelievably, even DDR3 isn't spared. Our suppliers have been quoting us much higher prices for DDR3 for months now, and we're experiencing persistent stock shortages. Fabs are abandoning legacy nodes to prioritize AI capacity, making it rough even for maintaining old gear.

It isn't really unbelievable. Anyone who could sub in DDR4 for their projects would do so which increased the price. And then anyone who was still using DDR4 for projects would respond to the increased price by moving to cheaper DDR3 if they could. It wouldn't take much of an unexpected demand increase to move the needle since I don't believe much DDR3 or DDR4 is even being manufactured anymore. And then you have the supply side: Increased prices of upgrades will cause many of them to be delayed or cancelled denying the refurb/used market supply of the old hardware.

The main downside is shifting from inline validation to out-of-band state syncing. For handshakes to stay small, browsers must constantly cache fresh "landmarks." If a device has been offline and hits a flaky hotel captive portal, it lacks these landmarks and triggers a fallback with massive inline ML-DSA signatures—bloating the handshake to 10KB+ exactly when the network is at its worst. It essentially turns a crypto size problem into a browser background syncing challenge.