If the block feature goes away, I guarantee it will come back for - at the very least - the highest tier of paid accounts almost immediately afterwards.
I can't imagine any of the large corps that still use Xitter for customer communication will be happy not being able to block serial trolls. Or people with legitimate grievances who won't go away.
Could be worse. I never liked the idea of blocking "hiding" your content from other people to begin with. It makes it too easy to give trolls the confirmation they succeeded in getting under your skin, encouraging them to make another account to continue harassing their victim.