Well, stranger things have happened (uhm, Lindsey & Stevie actually being back in Fleetwood Mac, for one!), so anything is possible... and it's definitely something I'd be all for.
The most effective way I can see that kind of collaboration working, is if Stevie wrote lyrics to music Lindsey has written... and then they work together to make the songs as tight and perfect as possible. Working out all the harmonies and everything, as they go.
Such as they did for "Frozen Love."
I think their lyrical styles are too different for them to each write the lyrics.
Though I'm sure it could be done if they really wanted to... but there might be some knock-down, drag-out fights along the way!
