A spin-off about Methos would be cool. IMO Peter Wingfield is a much better actor than Adrian Paul. Admittedly AP is more decorative, but you can find good looking men galore in fashion magazines wheras good actors are a rare sight nowadays.
As we saw in Highlander IV even good actors can not save a bad movie, but as Methos is supposed to be some 4000 years old there ought to be enough good plots for several seasons.
He could meet Gilgamesh and Cleopatra, watch the library in Alexandria be burned down, watch Socrates die, meet Jesus, Mohammed and Buddha, maybe even meet maythical persons like Beowulf and King Arthur. Who knows, he could even find the Grail.
And don't forget the big turning point when the apocalyptic horseman became the friendly philosopher. In the Highlander-series we never learned how and why this happened.
The producers have a chance here to make an excellent and successful spin-off. Let's hope that they'll finally take it.