Looks like the time has finally come for these two devices. Android developer and Google employee Jean-Baptiste Queru wrote this in the Android 4.2 device support statement:
-There is no support for 4.2 on Nexus S and Xoom. Those devices should continue using 4.1.2.
When asked for clarification, he had no comment. This may very well mean the end to official updates for the two devices. While this may seem bleak, they both had a very good run for Android devices. The Nexus S was updated for two whole years, going through two major updates. The XOOM also got two major updates. And yes, both are old and slow devices that might not handle the bit of extra load Android 4.2 has. The Nexus S has only 512MB of RAM, and the XOOM has a Tegra 2 (that should speak for itself).
They had a good run, but don’t think it’s all over. The developer community won’t just stop; both devices will have 4.2 ROMs available quite fast. If you want to stay up to date, you’ll have to take the risk and root. But you’ll be extending the life of your device for a while longer.