When/if SMF 2.1 reaches a stable enough state and we've upgraded to it, they include a lot of responsive changes to the SMF default theme which I will rework our theme based on.
On the other hand, if SMF 2.1 takes too long to come out (I quite like SMF, but their development has been very slow lately) or otherwise just isn't up to snuff, we may end up having to migrate over to XenForo 2.0.
Either way, I can't give a timeframe for it.