The sleeves for this set, IMHO, would be something revolving around the Eeveelutions, more so toward Glaceon and Leafeon. However, Garchomp is another good candidate for this set. Upon looking at some of the latest trend, from SW to GE, they used pokemon from the pack art for the sleeves, so maybe that'll be the case again.
Honestly though, I HOPE they do the Lucario type of sleeves. They were very durable, but these Electivire, Weevile, etc. sleeves are just terrible quality that won't last a person very long at all.