Based on my experience watching non-techy users using browsers, and the design goal of Chrome OS, I don't think it is going to happen anytime soon.

Quick question: if you can split into two windows, why not 4? 8? Then you end up with a Window-based UI, which is more complicated than simple tab-based.

It is very limiting, but I don't think normal people who just check their emails and Facebook updates would find annoying.