This is a very difficult thing to implement, it could potentially break many of the add-ons, and could introduce some very confusing UI elements.
That said, we’re interested to get more ideas from you for how something like this might work. Feel free to post your comments below.
I would like to see the ability to at least arrange the panes. I agree with the OP that undocking the console from the ISE would be nice. PowerShellPlus has had the capability for years; the problem with PowerShellPlus is that it's never updated.
@Casey - a second session is not the same thing. The variables are live in the integrated console.