What do you expect/hope Nexon throws in with Big Bang?

there's many other things that come in events that are not made available to players in the future. most itcg items, witch belts, explorer rings, etc.

All those items are now replaced with new stuff. Potential system nailed the coffin shut on most iTCG items and witch belts are easily replaced by immortal pharaoh belts. The one exeption would be explorer rings. Every medal you miss would hurt you if they all stack. Granted it's borderline ocd to care about every last stat points, but we all know that's the way most maplers work.