What will be banned? Maybe we will see unbans?

I play only Explorer, so I hope for [[Karn, the Great Creator]] ban. Without wishboard MonoG will need to have answers in maindeck, so [[Storm the Festival]] won't be as consistent as now. Midrange deck, that have combo-finisher ( with [[Pestilent Cauldron]] ) and can loop [[The Stone Brain]], seems too strong right now.

About unbans. I don't know about 2 cards:

• [[Nexus of Fate]]
• [[Leyline of Abundance]]

Will they break current Pioneer? The rest can't be unbanned.